Yes, I believe it was. He was switched with the other Lorca with the transporters of the Buran, the same way Kirk and team were... later actually. He then apparently got the Buran to self-destruct, probably because the others saw that he wasn't the real Lorca, and managed to get assigned to the Discovery, one of two ships that could get him back to his universe.
Which episode because I'm watching season 1 to 3 again and so far I like Lorca in season 1 but which episode is the switch explained?