Bah it's like movies using the same actors and actresses. Not a big deal at all...
That depends highly on the story, for me. Sometimes it works ok. Sometimes it just doesn't. I.E. Toby Mcguire is Spider-Man. I just wouldn't be able to see him as another super hero, like Superman, Batman, or whoever. It would just throw off my sensors. lol
Pierce Brosnan quit 007 due to that, if I remember correctly. He declined to do another one cause he didn't wanna be known as just James Bond in the eyes of the viewers/fans. Sean Connery was able to play multiple huge roles like that, but it doesn't always work for every actor.
Sylvester Stallone with Rocky and Rambo...ok...but now every time I watch an Expendables movie, my mind just sees him as John Rambo shooting people. lol