It’s been a long time since I read those books. If my googling & memory is correct, they at some point during the 74th Hunger Games announced that two victors from the same district would be allowed, then revoked that to ensure Katniss and Peeta would kill each other, then backflipped to allow the original agreement when they threatened a double suicide. Have I got that right?
I haven’t put a huge amount of thought into this, but I suspect their iconicness would be much lessened, and thus their ability to inspire rebellion in the future.