Errore 2 Grandle

Salve a tutti, ho un problema con lo sviluppo della mia applicazione: quando cerco di eseguirla mi esce il seguente errore:
Execution failed for task ':Mysecrets:dexDefaultFlavorDebug'.
> com.android.ide.common.internal.LoggedErrorExcepti on: Failed to run command:
C:\Program Files (x86)\Android\android-studio\sdk\build-tools\19.0.0\dx.bat --dex --output C:\Users\UtentePc\AndroidStudioProjects\MySecrets\ Mysecrets\build\libs\Mysecrets-defaultFlavor-debug.dex C:\Users\UtentePc\AndroidStudioProjects\MySecrets\ Mysecrets\build\classes\defaultFlavor\debug C:\Users\UtentePc\AndroidStudioProjects\MySecrets\ Mysecrets\build\dependency-cache\defaultFlavor\debug C:\Users\UtentePc\AndroidStudioProjects\MySecrets\ Mysecrets\build\pre-dexed\defaultFlavor\debug\classes-a2a34e7e3d0a97b74f51fd1f0835f5d13463372c.jar C:\Users\UtentePc\AndroidStudioProjects\MySecrets\ Mysecrets\build\pre-dexed\defaultFlavor\debug\support-v4-18.0.0-ea370c15186367a9f4015a837a7bab1e.jar C:\Users\UtentePc\AndroidStudioProjects\MySecrets\ Mysecrets\build\pre-dexed\defaultFlavor\debug\support-v4-19.0.0-0833b290331067bf347e927815c0e47996af9a37.jar
Error Code:
2
Output:
UNEXPECTED TOP-LEVEL EXCEPTION:
com.android.dex.DexException: Multiple dex files define Landroid/support/v4/accessibilityservice/AccessibilityServiceInfoCompat$AccessibilityServic eInfoVersionImpl;
at com.android.dx.merge.DexMerger.readSortableTypes(D exMerger.java:593)
at com.android.dx.merge.DexMerger.getSortedTypes(DexM erger.java:551)
at com.android.dx.merge.DexMerger.mergeClassDefs(DexM erger.java:532)
at com.android.dx.merge.DexMerger.mergeDexes(DexMerge r.java:169)
at com.android.dx.merge.DexMerger.merge(DexMerger.jav a:187)
at com.android.dx.command.dexer.Main.mergeLibraryDexB uffers(Main.java:439)
at com.android.dx.command.dexer.Main.runMonoDex(Main. java:287)
at com.android.dx.command.dexer.Main.run(Main.java:23 0)
at com.android.dx.command.dexer.Main.main(Main.java:1 99)
at com.android.dx.command.Main.main(Main.java:103)


qualcuno saprebbe spiegarmi la causa di ciò? grazie a tutti