Revert "Revert "Turn off duplicate-classes checking""

This reverts commit 18a1827a159f1b235f3fcc934f428059185f550e.

Bug: 21333911

(cherry picked from commit 0fc16a09b4d2323f9c2b6aabc81ce120b278329b)

Change-Id: I8cb96efbf7151b238f3ee137a938b20ddfaf0ebc
2 files changed