She was probably on your "voided villager's line-up". Basically if you visit an island and the host has voided villagers, then they get added to this some sort of queue, so basically if you have an open plot then any random villager from your void-queue can move into that plot, and they may have stuff from their old island or say they came from a different island.
sorry if u already knew this lol but i hope it helps all the same xd