diff --git a/compile/api/src/main/scala/sbt/ClassToAPI.scala b/compile/api/src/main/scala/sbt/ClassToAPI.scala
index 8511d3599..9589865ec 100644
--- a/compile/api/src/main/scala/sbt/ClassToAPI.scala
+++ b/compile/api/src/main/scala/sbt/ClassToAPI.scala
@@ -89,10 +89,8 @@ object ClassToAPI {
   }
 
   /** TODO: over time, ClassToAPI should switch the majority of access to the classfile parser */
-  private[this] def classFileForClass(c: Class[_]): ClassFile = {
-    val file = new java.io.File(IO.classLocationFile(c), s"${c.getName.replace('.', '/')}.class")
-    classfile.Parser.apply(file)
-  }
+  private[this] def classFileForClass(c: Class[_]): ClassFile =
+    classfile.Parser.apply(IO.classfileLocation(c))
 
   private[this] def lzyS[T <: AnyRef](t: T): xsbti.api.Lazy[T] = lzy(t)
   def lzy[T <: AnyRef](t: => T): xsbti.api.Lazy[T] = xsbti.SafeLazy(t)
diff --git a/compile/src/main/scala/sbt/compiler/javac/DiagnosticsReporter.scala b/compile/src/main/scala/sbt/compiler/javac/DiagnosticsReporter.scala
index bb1b144e6..40958d36f 100644
--- a/compile/src/main/scala/sbt/compiler/javac/DiagnosticsReporter.scala
+++ b/compile/src/main/scala/sbt/compiler/javac/DiagnosticsReporter.scala
@@ -14,6 +14,10 @@ import javax.tools.Diagnostic.NOPOS
 final class DiagnosticsReporter(reporter: Reporter) extends DiagnosticListener[JavaFileObject] {
   val END_OF_LINE_MATCHER = "(\r\n)|[\r]|[\n]"
   val EOL = System.getProperty("line.separator")
+
+  private[this] var errorEncountered = false
+  def hasErrors: Boolean = errorEncountered
+
   private def fixedDiagnosticMessage(d: Diagnostic[_ <: JavaFileObject]): String = {
     def getRawMessage = d.getMessage(null)
     def fixWarnOrErrorMessage = {
@@ -110,6 +114,7 @@ final class DiagnosticsReporter(reporter: Reporter) extends DiagnosticListener[J
           if (sourceUri.isDefined) s"${sourceUri.get}:${if (line.isDefined) line.get else -1}"
           else ""
       }
+    if (severity == Severity.Error) errorEncountered = true
     reporter.log(pos, msg, severity)
   }
 }
diff --git a/compile/src/main/scala/sbt/compiler/javac/LocalJava.scala b/compile/src/main/scala/sbt/compiler/javac/LocalJava.scala
index 42ef0ed6e..b3b7a680d 100644
--- a/compile/src/main/scala/sbt/compiler/javac/LocalJava.scala
+++ b/compile/src/main/scala/sbt/compiler/javac/LocalJava.scala
@@ -74,6 +74,11 @@ final class LocalJavaCompiler(compiler: javax.tools.JavaCompiler) extends JavaCo
       log.warn("Javac is running in 'local' mode. These flags have been removed:")
       log.warn(invalidOptions.mkString("\t", ", ", ""))
     }
-    compiler.getTask(logWriter, fileManager, diagnostics, cleanedOptions.asJava, null, jfiles).call()
+    val success = compiler.getTask(logWriter, fileManager, diagnostics, cleanedOptions.asJava, null, jfiles).call()
+
+    // The local compiler may report a successful compilation even though there are errors (e.g. encoding problems in the
+    // source files). In a similar situation, command line javac reports a failed compilation. To have the local java compiler
+    // stick to javac's behavior, we report a failed compilation if there have been errors.
+    success && !diagnostics.hasErrors
   }
 }
\ No newline at end of file
diff --git a/ivy/src/main/scala/sbt/Ivy.scala b/ivy/src/main/scala/sbt/Ivy.scala
index b8540fd68..ef9b695e9 100644
--- a/ivy/src/main/scala/sbt/Ivy.scala
+++ b/ivy/src/main/scala/sbt/Ivy.scala
@@ -536,14 +536,18 @@ private[sbt] object IvySbt {
     {
       import IvyRetrieve.toModuleID
       val dds = moduleID.getDependencies
-      inconsistentDuplicateWarning(dds map { dd => toModuleID(dd.getDependencyRevisionId) })
+      val deps = dds flatMap { dd =>
+        val module = toModuleID(dd.getDependencyRevisionId)
+        dd.getModuleConfigurations map (c => module.copy(configurations = Some(c)))
+      }
+      inconsistentDuplicateWarning(deps)
     }
 
   def inconsistentDuplicateWarning(dependencies: Seq[ModuleID]): List[String] =
     {
       val warningHeader = "Multiple dependencies with the same organization/name but different versions. To avoid conflict, pick one version:"
       val out: mutable.ListBuffer[String] = mutable.ListBuffer()
-      (dependencies groupBy { dep => (dep.organization, dep.name) }) foreach {
+      (dependencies groupBy { dep => (dep.organization, dep.name, dep.configurations) }) foreach {
         case (k, vs) if vs.size > 1 =>
           val v0 = vs.head
           (vs find { _.revision != v0.revision }) foreach { v =>
diff --git a/ivy/src/test/scala/InconsistentDuplicateSpec.scala b/ivy/src/test/scala/InconsistentDuplicateSpec.scala
index b9f4a05ef..34a5a441f 100644
--- a/ivy/src/test/scala/InconsistentDuplicateSpec.scala
+++ b/ivy/src/test/scala/InconsistentDuplicateSpec.scala
@@ -9,6 +9,7 @@ class InconsistentDuplicateSpec extends Specification {
 
   Duplicate with different version should
     be warned                                                   $warn1
+    not be warned if in different configurations                $nodupe2
 
   Duplicate with same version should
     not be warned                                               $nodupe1
@@ -25,4 +26,8 @@ class InconsistentDuplicateSpec extends Specification {
 
   def nodupe1 =
     IvySbt.inconsistentDuplicateWarning(Seq(akkaActor230Test, akkaActor230)) must_== Nil
+
+  def nodupe2 =
+    IvySbt.inconsistentDuplicateWarning(Seq(akkaActor214, akkaActor230Test)) must_== Nil
+
 }
diff --git a/notes/0.13.10/fix-duplicate-warnings.markdown b/notes/0.13.10/fix-duplicate-warnings.markdown
new file mode 100644
index 000000000..a8e9c8bed
--- /dev/null
+++ b/notes/0.13.10/fix-duplicate-warnings.markdown
@@ -0,0 +1,13 @@
+
+  [@Duhemm]: http://github.com/Duhemm
+  [1933]: https://github.com/sbt/sbt/issues/1933
+  [2258]: https://github.com/sbt/sbt/pull/2258
+
+### Fixes with compatibility implications
+
+### Improvements
+
+### Bug fixes
+
+- Fixes [#1933][1933] duplicate warnings for artifacts in distinct configurations [#2258][2258] by
+  [@Duhemm][@Duhemm]
diff --git a/notes/0.13.10/local-java-report-errors.md b/notes/0.13.10/local-java-report-errors.md
new file mode 100644
index 000000000..8c36fb710
--- /dev/null
+++ b/notes/0.13.10/local-java-report-errors.md
@@ -0,0 +1,12 @@
+
+  [@Duhemm]: http://github.com/Duhemm
+  [2228]: https://github.com/sbt/sbt/issues/2228
+  [2271]: https://github.com/sbt/sbt/pull/2271
+
+### Fixes with compatibility implications
+
+### Improvements
+
+### Bug fixes
+
+- Report java compilation as failed if the local java compiler reported compilation errors (issue [#2228][2228]) [#2271][2271] by [@Duhemm][@Duhemm]
diff --git a/util/classfile/src/main/scala/sbt/classfile/ClassFile.scala b/util/classfile/src/main/scala/sbt/classfile/ClassFile.scala
index 3f1a0d915..e78b9cfd2 100644
--- a/util/classfile/src/main/scala/sbt/classfile/ClassFile.scala
+++ b/util/classfile/src/main/scala/sbt/classfile/ClassFile.scala
@@ -10,7 +10,6 @@ import java.io.File
 private[sbt] trait ClassFile {
   val majorVersion: Int
   val minorVersion: Int
-  val fileName: String
   val className: String
   val superClassName: String
   val interfaceNames: Array[String]
diff --git a/util/classfile/src/main/scala/sbt/classfile/Parser.scala b/util/classfile/src/main/scala/sbt/classfile/Parser.scala
index 16c5bf656..06a5e70e4 100644
--- a/util/classfile/src/main/scala/sbt/classfile/Parser.scala
+++ b/util/classfile/src/main/scala/sbt/classfile/Parser.scala
@@ -4,6 +4,7 @@
 package sbt
 package classfile
 
+import java.net.URL
 import java.io.{ DataInputStream, File, InputStream }
 import scala.annotation.switch
 
@@ -15,15 +16,19 @@ import scala.annotation.switch
 import Constants._
 
 private[sbt] object Parser {
-  def apply(file: File): ClassFile = Using.fileInputStream(file)(parse(file.getAbsolutePath)).right.get
-  private def parse(fileName: String)(is: InputStream): Either[String, ClassFile] = Right(parseImpl(fileName, is))
-  private def parseImpl(filename: String, is: InputStream): ClassFile =
+  def apply(file: File): ClassFile =
+    Using.fileInputStream(file)(parse(file.toString)).right.get
+
+  def apply(url: URL): ClassFile =
+    Using.urlInputStream(url)(parse(url.toString)).right.get
+
+  private def parse(readableName: String)(is: InputStream): Either[String, ClassFile] = Right(parseImpl(readableName, is))
+  private def parseImpl(readableName: String, is: InputStream): ClassFile =
     {
       val in = new DataInputStream(is)
-      new ClassFile {
-        assume(in.readInt() == JavaMagic, "Invalid class file: " + fileName)
+      assume(in.readInt() == JavaMagic, "Invalid class file: " + readableName)
 
-        val fileName = filename
+      new ClassFile {
         val minorVersion: Int = in.readUnsignedShort()
         val majorVersion: Int = in.readUnsignedShort()
 
diff --git a/util/classfile/src/test/scala/sbt/classfile/ParserSpecification.scala b/util/classfile/src/test/scala/sbt/classfile/ParserSpecification.scala
new file mode 100644
index 000000000..aa1cb743e
--- /dev/null
+++ b/util/classfile/src/test/scala/sbt/classfile/ParserSpecification.scala
@@ -0,0 +1,24 @@
+package sbt
+package classfile
+
+import util.Try
+
+import org.scalacheck._
+import Prop._
+
+object ParserSpecification extends Properties("Parser") {
+  property("able to parse all relevant classes") =
+    Prop.forAll(classes) { (c: Class[_]) =>
+      Parser(IO.classfileLocation(c)) ne null
+    }
+
+  implicit def classes: Gen[Class[_]] =
+    Gen.oneOf(
+      this.getClass,
+      classOf[java.lang.Integer],
+      classOf[java.util.AbstractMap.SimpleEntry[String, String]],
+      classOf[String],
+      classOf[Thread],
+      classOf[Properties]
+    )
+}
diff --git a/util/io/src/main/scala/sbt/IO.scala b/util/io/src/main/scala/sbt/IO.scala
index 0fd5f52ad..179faa7e2 100644
--- a/util/io/src/main/scala/sbt/IO.scala
+++ b/util/io/src/main/scala/sbt/IO.scala
@@ -36,39 +36,43 @@ object IO {
   val utf8 = Charset.forName("UTF-8")
 
   /**
-   * Returns a URL for the directory or jar containing the the class file `cl`.
+   * Returns a URL for the classfile containing the given class
    * If the location cannot be determined, an error is generated.
    */
-  def classLocation(cl: Class[_]): URL = {
-    val codeSource = cl.getProtectionDomain.getCodeSource
-    if (codeSource ne null) {
-      codeSource.getLocation
-    } else {
-      // NB: This assumes that classes without code sources are System classes, and thus located in
-      // jars. It assumes that `urlAsFile` will truncate to the containing jar file.
-      val clsfile = s"${cl.getName.replace('.', '/')}.class"
-      Option(ClassLoader.getSystemClassLoader.getResource(clsfile))
-        .flatMap {
-          urlAsFile
-        }.getOrElse {
-          sys.error("No class location for " + cl)
-        }.toURI.toURL
+  def classfileLocation(cl: Class[_]): URL = {
+    val clsfile = s"${cl.getName.replace('.', '/')}.class"
+    try {
+      Stream(Option(cl.getClassLoader), Some(ClassLoader.getSystemClassLoader)).flatten.flatMap { classLoader =>
+        Option(classLoader.getResource(clsfile))
+      }.headOption.getOrElse {
+        sys.error("No class location for " + cl)
+      }
+    } catch {
+      case e =>
+        e.printStackTrace()
+        throw e
     }
   }
 
   /**
-   * Returns the directory or jar file containing the the class file `cl`.
-   * If the location cannot be determined or it is not a file, an error is generated.
+   * Returns the directory or jar file containing the class file `cl`.
+   * If the location cannot be determined or if it is not a file, an error is generated.
    * Note that Java standard library classes typically do not have a location associated with them.
    */
-  def classLocationFile(cl: Class[_]): File = toFile(classLocation(cl))
+  def classLocationFile(cl: Class[_]): File = {
+    val classURL =
+      Option(cl.getProtectionDomain.getCodeSource).getOrElse {
+        sys.error("No class location for " + cl)
+      }.getLocation
+    toFile(classURL)
+  }
 
   /**
    * Returns a URL for the directory or jar containing the class file for type `T` (as determined by an implicit Manifest).
    * If the location cannot be determined, an error is generated.
    * Note that Java standard library classes typically do not have a location associated with them.
    */
-  def classLocation[T](implicit mf: SManifest[T]): URL = classLocation(mf.runtimeClass)
+  def classfileLocation[T](implicit mf: SManifest[T]): URL = classfileLocation(mf.runtimeClass)
 
   /**
    * Returns the directory or jar file containing the the class file for type `T` (as determined by an implicit Manifest).
diff --git a/util/io/src/test/scala/sbt/IOSpecification.scala b/util/io/src/test/scala/sbt/IOSpecification.scala
index 882f147c5..e932334b6 100644
--- a/util/io/src/test/scala/sbt/IOSpecification.scala
+++ b/util/io/src/test/scala/sbt/IOSpecification.scala
@@ -18,6 +18,7 @@ object IOSpecification extends Properties("IO") {
     Gen.oneOf(
       this.getClass,
       classOf[java.lang.Integer],
+      classOf[java.util.AbstractMap.SimpleEntry[String, String]],
       classOf[String],
       classOf[Thread],
       classOf[Properties]