Apparently I can have my cake and eat it too O_O (A lot of info added)

[Bilaz]

I accidentally created a new post instead of editing my old one, I can't find out how to delete it but I thought I'd take this moment to quote

Ah, okay, appreciate the clarification. I thought the island was still backed up to the cloud on both consoles, so I was thinking, "How could Nintendo have not tested for this scenario?"

to let them know about the update. I'm sorry for posting misinformation without checking

 

[Bilaz]

More updated info
I can't connect locally between the two islands, while I could do that when I had non duplicate islands
So maybe this is the cheating protection