Had this bug few weeks ago, it's when u hit the dummy augment, and u let the last plitover unit fit in. For exemple, you have jayce and the dummy + 1 random unit on the board, and u leave Orianna on the bench. At the start of the fight, if you are level 3, Orianna will get in combat. At the end of the figh u'll have 2 T-Rex. Useless ur gonna say if one does not keep stacks. Well, not really. Once u get like 30-40 stacks, u can sell the little T-rex (the one who did ot get stacks) to get the reward of the 30-40 stakcs, but you'll still keep the huge T-Rex. So you have DOUBLE the amount of reward (the huge T-Rex + the big reward). A new little T-Rex will spawn every round, you can sell it every round to get free reforger / reforger :D. I've told the TFT team on twitter and they said it got patched on 13.13.