In the top of the Eclysia Pyramid, when you have to fight as Adam, I lost. When I respawned, the character was invisible and had Adam's ID. I thought that I could go back to the top and repeat only the last battle.
When I retried and won, my character was overriden with Adam. I got his team and even Delpha and all his items in exchange of mine, including key items.
I don't have any backup saves and I D-saved after I regained control with the character because I thought everything worked out fine.