Can I just replace one tire on my GT?

I recently had my winter tires put on at a reputable tire place. They damaged one of my summer tires upon dismount and they apologized and said they would replace it free of charge when I came back in to switch them back. I was a stress case that day due to personal issues and while I was concerned changing just the one tire seemed off I didn’t fight, just ensured they guaranteed that offer in writing and left it. Now I’m left in a bit of confusion about it all. What do you all suggest?