I think it's quite explicit => ACRA.init method is called twice (or more)
Why did you initialize ACRA in onConfigurationChanged method ?
onConfigurationChanged is called each time your configuration is changed (good deduction Dr Watson...): for example when you change the orientation of your handset, ...
You should initialize ACRA in your Application.onCreate method (which is called only once):
public class MyApplication extends Application {
@Override
public void onCreate() {
super.onCreate();
ACRA.init(this);
}
}