Android Studio: Duplicate files copied in APK META-INF/DEPENDENCIES when compile

Question

I exported my project from Eclipse and imported to Android Studio using the instructions in this link: http://developer.android.com/sdk/installing/migrate.html

When I build, I have an error:

Duplicate files copied in APK META-INF/DEPENDENCIES

After searching, I found a solution: add

packagingOptions {
    exclude 'META-INF/DEPENDENCIES'
}

into build.gradle. And it works!

But I don't understand why I had this error and why I've had to apply that fix. Can anybody explain?

Answer 1

While Scott Barta's answer is correct, is lacks a simple and common solution: just add

android {
    packagingOptions {
        exclude 'META-INF/DEPENDENCIES'
        exclude 'META-INF/NOTICE'
        exclude 'META-INF/LICENSE'
        exclude 'META-INF/LICENSE.txt'
        exclude 'META-INF/NOTICE.txt'
    }
}

to your build.gradle to ignore those duplicates.