diff --git a/android/todo.txt b/android/todo.txt
index 4bb5229fd..8a4d36e3b 100644
--- a/android/todo.txt
+++ b/android/todo.txt
@@ -1,6 +1,7 @@
 0204 android 
 X Android emulator not launching on Windows with 2.0 alpha releases
 X   http://code.google.com/p/processing/issues/detail?id=899
+X   http://code.google.com/p/processing/issues/detail?id=769
 X /opt/android using version #s again? fix build script (earlier)
 X smooth() is now the default
 
diff --git a/app/src/processing/app/Library.java b/app/src/processing/app/Library.java
index 08fea85fa..b72cb4455 100644
--- a/app/src/processing/app/Library.java
+++ b/app/src/processing/app/Library.java
@@ -219,27 +219,33 @@ public class Library extends InstalledContribution {
    * imports to specific libraries.
    * @param importToLibraryTable mapping from package names to Library objects
    */
-  public void addPackageList(HashMap<String,Library> importToLibraryTable) {
+//  public void addPackageList(HashMap<String,Library> importToLibraryTable) {
+  public void addPackageList(HashMap<String,ArrayList<Library>> importToLibraryTable) {
 //    PApplet.println(packages);
     for (String pkg : packageList) {
-      //    pw.println(pkg + "\t" + libraryFolder.getAbsolutePath());
-      Library library = importToLibraryTable.get(pkg);
-      if (library != null) {
-        if (!packageWarningMap.containsKey(pkg)) {
-          packageWarningMap.put(pkg, null);
+//          pw.println(pkg + "\t" + libraryFolder.getAbsolutePath());
+//      PApplet.println(pkg + "\t" + getName());
+//      Library library = importToLibraryTable.get(pkg);
+      ArrayList<Library> libraries = importToLibraryTable.get(pkg);
+      if (libraries == null) {
+        libraries = new ArrayList<Library>();
+        importToLibraryTable.put(pkg, libraries);
+      } else {
+        if (Base.DEBUG) {
           System.err.println("The library found in");
           System.err.println(getPath());
           System.err.println("conflicts with");
-          System.err.println(library.getPath());
-          System.err.println("which already defines the package " + pkg);
+          for (Library library : libraries) {
+            System.err.println(library.getPath());
+          }
+          System.err.println("which already define(s) the package " + pkg);
           System.err.println("If you have a line in your sketch that reads");
           System.err.println("import " + pkg + ".*;");
           System.err.println("Then you'll need to first remove one of those libraries.");
           System.err.println();
         }
-      } else {
-        importToLibraryTable.put(pkg, this);
       }
+      libraries.add(this);
     }
   }
 
diff --git a/app/src/processing/app/Mode.java b/app/src/processing/app/Mode.java
index 11d2cbbd5..93b44962b 100644
--- a/app/src/processing/app/Mode.java
+++ b/app/src/processing/app/Mode.java
@@ -25,7 +25,8 @@ public abstract class Mode {
 //  protected Tool formatter;
   
   // maps imported packages to their library folder
-  protected HashMap<String, Library> importToLibraryTable;
+//  protected HashMap<String, Library> importToLibraryTable;
+  protected HashMap<String, ArrayList<Library>> importToLibraryTable;
 
   // these menus are shared so that they needn't be rebuilt for all windows
   // each time a sketch is created, renamed, or moved.
@@ -115,7 +116,8 @@ public abstract class Mode {
 //    System.out.println("rebuildLibraryList()");
 
     // reset the table mapping imports to libraries
-    importToLibraryTable = new HashMap<String, Library>();
+//    importToLibraryTable = new HashMap<String, Library>();
+    importToLibraryTable = new HashMap<String, ArrayList<Library>>();
 
     coreLibraries = Library.list(librariesFolder);
     contribLibraries = Library.list(base.getSketchbookLibrariesFolder());
@@ -129,8 +131,28 @@ public abstract class Mode {
   }
   
   
-  public Library getLibrary(String name) {
-    return importToLibraryTable.get(name);
+  public Library getLibrary(String pkgName) throws SketchException {
+    ArrayList<Library> libraries = importToLibraryTable.get(pkgName);
+    if (libraries == null) {
+      return null;
+
+    } else if (libraries.size() > 1) {
+      String primary = "More than one library is competing for this sketch.";
+      String secondary = "The import " + pkgName + " points to multiple libraries:<br>";      
+      for (Library library : libraries) {
+        String location = library.getPath();
+        if (location.startsWith(getLibrariesFolder().getAbsolutePath())) {
+          location = "part of Processing";
+        }
+        secondary += "<b>" + library.getName() + "</b> (" + location + ")<br>";
+      }
+      secondary += "Extra libraries need to be removed before this sketch can be used."; 
+      Base.showWarningTiered("Duplicate Library Problem", primary, secondary, null);
+      throw new SketchException("Duplicate libraries found for " + pkgName + ".");
+    
+    } else {
+      return libraries.get(0);
+    }
   }
 
   
diff --git a/todo.txt b/todo.txt
index f73e0d38d..89b9cf069 100644
--- a/todo.txt
+++ b/todo.txt
@@ -4,6 +4,9 @@ X   http://code.google.com/p/processing/issues/detail?id=877
 X make note of when library is not available (serial) with error msg
 X   i.e. if running in 64-bit mode on OS X, can't do serial
 X update to Java 6u29 for Linux and Windows (OS X now updated)
+X don't show library conflict warning until someone tries to build 
+X   with code that actually calls on one of those packages
+X   too many people seem to think this is an error
 
 fixed in 2.0a3
 X Commenting via menu or shortcut does not set sketch to "need save"
@@ -18,10 +21,6 @@ X   otherwise ppl are copying really large files into a jar...
 _ move Movie Maker out to its own separate tool package (with separate build)
 _   http://code.google.com/p/processing/issues/detail?id=837
 
-_ don't show library conflict warning until someone tries to build 
-_   with code that actually calls on one of those packages
-_   too many people seem to think this is an error
-
 _ bad tool brings down the environment
 _   http://code.google.com/p/processing/issues/detail?id=798