Unable to merge dex

Error:Execution failed for task ':app:transformDexArchiveWithExternalLibsDexMergerForDebug'.

java.lang.RuntimeException: com.android.builder.dexing.DexArchiveMergerException: Unable to merge dex

build.gradle

defaultConfig {
...
minSdkVersion 14
    targetSdkVersion 26
    multiDexEnabled true
...
}
dependencies {
compile fileTree(include: ['*.jar'], dir: 'libs')
compile 'com.android.support:multidex:1.0.1'
implementation 'com.vodyasov:amr:0.5'
implementation 'com.squareup.picasso:picasso:2.5.2'
//for Inmobi
implementation 'com.android.support:design:27.0.2'
implementation 'com.android.support:appcompat-v7:27.0.2'
implementation 'com.android.support:support-v4:27.0.2'
testCompile 'junit:junit:4.12'
implementation 'com.google.android.gms:play-services:11.8.0'
}

AndroidManifest.xml

<application
    android:name=".App"
    ...
</application>

App.class

public class App extends Application {
@Override
protected void attachBaseContext(Context base) {
    super.attachBaseContext(base);
    MultiDex.install(this);
}
}