Android Studio: disabling “External build” to display error output create duplicate class errors

Question

I am starting my migration from Eclipse to Android Studio, and start playing with new projects on Studio.

My test project was working fine till I got some errors mes

Answer 1

So, just to let you know...

A few minutes after I posted my question, Google released an update to Android Studio (0.1.5) See link: https://plus.google.com/+AndroidDevelopers/posts/Y9vhvGaHCbh

Tor Norbye kindly answered my question in this community, and I am sharing here

So the workaround I quoted in the OP is no more mandatory.

Enabling again External build after upgrading Android Sudio let me see the real errors ( a library and some Gradle import that I fixed)

So, I consider the Android Studio upgrade as the best answer to this question...