Is it normal to make up a fake twin and pretend to be both of them?

So once at summer camp, I had one of my group members come up to me and I pretended that I didn't know who they were. When they further pressed me about it, I pretended I was a fake twin and I would switch up who I was when it was swim time, because all the groups swam at the same time and it wasn't just our group alone so I could get away with it. I never told him the truth, and the summer ended with him thinking I was two people. Anybody else ever do this?