Bet forensic testing on the ink shows one is modern ink from within the last year or two.
i sold an autograph that was 30 years old for 1000 dollars....the guy had it looked at and could tell how old the ink was. They can tell.
I had some exposure to document examination before I retired. It would take great skill to make such a close forgery free-hand. (Not that David Axelrod couldn’t find someone to do it). The signature differences could be explained by the difference in passing years. (But they’re still pretty close—a little TOO close—maybe a tracing?)
The difference in inks, however, could be readily disclosed through infra-red lighting. (And why Moore has asked for the original).