"Managed by" profiles (such as children's) should only ever be created under one person's account. The other should link to them as friends (the manager of those profiles would accept the friend request for them).
You start running into trouble with multiple copies of the same people under different accounts, since to Disney's eyes they're two different people that happen to have the same name. MagicBands on one account, tickets on the other, it becomes tangled up quite easily.
If one set doesn't have any tickets or MagicBands linked, you can delete them and just have the other parent connect as friends. But if there are tickets, Bands, etc linked to both, it'll require a call to the MDE Help Desk to sort out. (407) 939-4357
-Rob