Android Error: java.lang.IllegalArgumentException: already added:

I have a project with several library projects, all compile correctly:

When I try to Run it as Android app, I get errors:

UNEXPECTED TOP-LEVEL EXCEPTION:

java.lang.IllegalArgumentException: already added: Lcom/cyberwalkabout/gss/Worksheet;

[2012-06-06 20:54:42 - Food Trucks America] Dx at com.android.dx.dex.file.ClassDefsSection.add(ClassDefsSection.java:123)

...

org.eclipse.core.internal.jobs.Worker.run(Worker.java:54)

[2012-06-06 20:54:42 - Food Trucks America] Dx 108 errors; aborting

[2012-06-06 20:54:42 - Food Trucks America] Conversion to Dalvik format failed with error 1

SOLUTION:

I removed _src folders that were already included in my library projects. Project runs fine!