Error building .apk archive with Google Cardboard VR

I'm trying to build my VR project using Unity 5.6 and Google Cardboard. I'm getting the following error

 CommandInvokationFailure: Unable to convert classes into dex format.
 /Library/Java/JavaVirtualMachines/jdk1.8.0_131.jdk/Contents/Home/bin/java -Xmx2048M -Dcom.android.sdkmanager.toolsdir="/Users/mymac/Library/Android/sdk/tools" -Dfile.encoding=UTF8 -jar "/Applications/Unity/PlaybackEngines/AndroidPlayer/Tools/sdktools.jar" -
 
 stderr[
 Uncaught translation error: java.lang.IllegalArgumentException: already added: Lcom/google/vr/cardboard/DisplaySynchronizer;
 Uncaught translation error: java.lang.IllegalArgumentException: already added: Lcom/google/vr/cardboard/FrameMonitor;
 Uncaught translation error: java.lang.IllegalArgumentException: already added: Lcom/google/vr/cardboard/NFCUtils;
 Uncaught translation error: java.lang.IllegalArgumentException: already added: Lcom/google/vr/cardboard/NFCUtils$1;
 Uncaught translation error: java.lang.IllegalArgumentException: already added: Lcom/google/vr/cardboard/TransitionView;
 Uncaught translation error: java.lang.IllegalArgumentException: already added: Lcom/google/vr/cardboard/TransitionView$1;
 Uncaught translation error: java.lang.IllegalArgumentException: already added: Lcom/google/vr/cardboard/TransitionView$2;
 Uncaught translation error: java.lang.IllegalArgumentException: already added: Lcom/google/vr/cardboard/TransitionView$3;
 Uncaught translation error: java.lang.IllegalArgumentException: already added: Lcom/google/vr/cardboard/TransitionView$TransitionListener;
 
 UNEXPECTED TOP-LEVEL EXCEPTION:
 java.lang.RuntimeException: Translation has been interrupted
     at com.android.dx.command.dexer.Main.processAllFiles(Main.java:613)
     at com.android.dx.command.dexer.Main.runMonoDex(Main.java:311)
     at com.android.dx.command.dexer.Main.run(Main.java:277)
     at com.android.dx.command.dexer.Main.main(Main.java:245)
     at com.android.dx.command.Main.main(Main.java:106)
     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
     at java.lang.reflect.Method.invoke(Method.java:498)
     at SDKMain.main(SDKMain.java:129)
 Caused by: java.lang.InterruptedException: Too many errors
     at com.android.dx.command.dexer.Main.processAllFiles(Main.java:605)
     ... 9 more
 ]
 stdout[
 processing archive /Users/mymac/Desktop/project/Temp/StagingArea/android-libraries/gvr-permissionsupport-release/libs/./classes.jar...
 processing com/google/gvr/permissionsupport/BuildConfig.class...
 processing com/google/gvr/permissionsupport/PermissionsFragment.class...
 processing com/google/gvr/permissionsupport/PermissionsFragment$1.class...
 processing com/google/gvr/permissionsupport/PermissionsFragment$PermissionsCallback.class...
 processing com/google/gvr/permissionsupport/TransitionVRActivity.class...
 processing com/google/gvr/permissionsupport/TransitionVRActivity$1.class...
 ignored resource mymac/Temp/StagingArea/android-libraries/gvr/libs/./armeabi-v7a/libgvr.so
 processing archive

Looking around I found that it might be a .jar/.aar files duplication error, so I have looked for them in my project:

 mymac$ find . | grep .aar
 ./Assets/Plugins/Android/gvr-permissionsupport-release.aar
 ./Assets/Plugins/Android/gvr-permissionsupport-release.aar.meta
 ./Temp/StagingArea/aar
 ./Temp/StagingArea/aar/gvr-permissionsupport-release.aar
 ./Temp/StagingArea/aar/gvr.aar
 ./Temp/StagingArea/aar/unitygvr.aar
 
 mymac$ find . | grep .jar
 ./Assets/Plugins/Android/unityvractivity.jar
 ./Assets/Plugins/Android/unityvractivity.jar.meta
 ./Temp/StagingArea/android-libraries/gvr/libs/classes.jar
 ./Temp/StagingArea/android-libraries/gvr-permissionsupport-release/libs/classes.jar
 ./Temp/StagingArea/android-libraries/unitygvr/libs/classes.jar
 ./Temp/StagingArea/bin/classes.jar
 ./Temp/StagingArea/plugins/libprotobuf-java-nano.jar
 ./Temp/StagingArea/plugins/unityvractivity.jar
 

ad you can see there are no duplications as all the other files are copy created in /Temp at build time. Not sure about how to proceed.