Solved: Conversion to Dalvik format failed with error 1

UNEXPECTED TOP-LEVEL EXCEPTION:

java.lang.IllegalArgumentException: already added: Lcom/badlogic/gdx/Application$ApplicationType;

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[2012-05-27 02:20:03 - skeletonAppAndroid] Conversion to Dalvik format failed with error 1

This error already made me frustated for some hours. I  just wanna share the solution : There are double external .jar library in your directory project but in eclipse file view, that doesn’t displayed. so you must inspect that via windows file explorer.  If there are double  external .jar library, delete one of  them. The problem : somehow, when project clean command is executed, external .jar library is copied to “bin\classes” (in my case) that cause double external .jar file. I don’t know , it was eclipse – adt bug, or there are wrong  project’s setting. Other suggestion : update your adt plugin, because so many bug is fixed in latest version. it is adt20 now.