Same Obsession, Same Person
In Disney movies, stepmoms are always evil. They’ve never heard of stepmoms adopting their stepchildren and becoming loving mothers. It’s an impossibility in the eyes of an evil corporation, but we digress. If you rewatch Tangled and Snow White and the Seven Dwarfs, you’ll notice how Mother Gothel and the Evil Queen look oddly alike.
That’s because they’re one and the same. The OP provided their evidence to support this claim, which, to us, sounds fairly reasonable. In this theory, the Evil Queen would’ve faked her own death to throw hunters off her trail, making it much easier to keep Rapunzel in her tower.