Why im getting this error while packing destribution apk?

====15-01-2018 6.36.47 PM====PERFORMING FINAL APK PACKAGE OPERATION================================================
UATHelper: Packaging (Android (ETC1)): Making .apk with Ant… (note: it’s safe to ignore javac obsolete warnings)
UATHelper: Packaging (Android (ETC1)): [javac] Note: Some input files use or override a deprecated API.
UATHelper: Packaging (Android (ETC1)): [javac] Note: Recompile with -Xlint:deprecation for details.
UATHelper: Packaging (Android (ETC1)): [proguard] Warning: can’t write resource [META-INF/MANIFEST.MF] (Duplicate zip entry [classes.jar:META-INF/MANIFEST.MF])
UATHelper: Packaging (Android (ETC1)): [proguard] Warning: can’t write resource [META-INF/MANIFEST.MF] (Duplicate zip entry [classes.jar:META-INF/MANIFEST.MF])
UATHelper: Packaging (Android (ETC1)): [proguard] Warning: can’t write resource [META-INF/MANIFEST.MF] (Duplicate zip entry [classes.jar:META-INF/MANIFEST.MF])
UATHelper: Packaging (Android (ETC1)): [proguard] Warning: can’t write resource [META-INF/MANIFEST.MF] (Duplicate zip entry [classes.jar:META-INF/MANIFEST.MF])
UATHelper: Packaging (Android (ETC1)): [proguard] Warning: can’t write resource [META-INF/MANIFEST.MF] (Duplicate zip entry [classes.jar:META-INF/MANIFEST.MF])
UATHelper: Packaging (Android (ETC1)): [proguard] Warning: can’t write resource [META-INF/MANIFEST.MF] (Duplicate zip entry [classes.jar:META-INF/MANIFEST.MF])
UATHelper: Packaging (Android (ETC1)): [proguard] Warning: can’t write resource [META-INF/MANIFEST.MF] (Duplicate zip entry [classes.jar:META-INF/MANIFEST.MF])
UATHelper: Packaging (Android (ETC1)): [proguard] Warning: can’t write resource [META-INF/MANIFEST.MF] (Duplicate zip entry [classes.jar:META-INF/MANIFEST.MF])
UATHelper: Packaging (Android (ETC1)): [proguard] Warning: can’t write resource [META-INF/MANIFEST.MF] (Duplicate zip entry [classes.jar:META-INF/MANIFEST.MF])