I moved over from an iPhone 6s, and after having some difficulties, I put it my old SIM card. I wasn’t sure which sim I should have in there, so I ended up swapping them back and forth a few times (Stupid idea, I know.) Anyway, I’m noticing in my Settings>General, it’s now listing two SIMS. I’m not sure what happened, if I put the sim on the backside of the tray one time, but I’m just concerned this will cause issues going forward.