Their names changed but did they actually gain other properties with a new welder or did Luna and Celestia just get the names wrong, because with the first option hey could be corrupted or given new properties with new individuals, which both would be interesting and explain why they acted differently when they hit luna the second time. But the second option also makes sense because of how well they embody the original names.
any thoughts?

Maybe the Elements were meant for only Twilight and her amigos to use, and Tia and Loony used the Elements only as stewards. Keepers. Replacements until the ponies meant to bear them showed up.

My headcanon, anyway.