How to resolve Duplicate files copied in APK META-INF/rxjava.properties

I had the same issue.
In my case I am using Retrofit2 but I assume that the issue is with the rx libraries

This is the build.gradle (module:app) I am using and in my case works.

compile 'com.squareup.retrofit2:retrofit:2.0.2'
compile 'com.squareup.retrofit2:converter-gson:2.0.2'
compile 'com.squareup.retrofit2:adapter-rxjava:2.0.2'

compile 'io.reactivex:rxandroid:1.1.0' //<-use this
compile 'io.reactivex:rxjava:1.1.3'    //<-use this

compile 'com.squareup.okhttp3:okhttp:3.1.2'
compile 'com.squareup.okhttp3:logging-interceptor:3.0.1'

Anyway there is one better solution as you can see on the top

I had the same problem. The way I fixed it is adding the packagingOptions in app gradle as described in Duplicated file rxjava.properties

android {

    defaultConfig {
    }
    buildTypes {
    }
    packagingOptions{
        exclude 'META-INF/rxjava.properties'
    }
}

I also have the same problem but easily removed duplicated "comment" all Rxjava related dependencies that it doesn't use in my code.

//RxJava removes or comment duplicated and not used dependencies.
      //  implementation 'com.squareup.retrofit2:adapter-rxjava:2.4.0'
       // implementation 'io.reactivex.rxjava2:rxandroid:2.0.2'
       // implementation 'io.reactivex.rxjava2:rxjava:2.1.13'