Okay so Ryan Reynolds reported that he can play two characters from two different universes. He was referring to playing both Deadpool and Green Lantern. We know this is possible since Halle Berry already played both Storm and Catwoman.
 
Only one problem. Ryan Reynolds already played Hannibal King in Blade: Trinity before he played Deadpool in X-Men Origins: Wolverine. He was also reported to play Wally West in the Flash movie. Now he is playing Hal Jordan in Green Lantern. Of course he can play a DC character and a Marvel character but you cannot play two.
 
Also, Ray Stevenson played Frank Castle in Punisher: War Zone and is now going to be playing Volstagg in Thor. These actors are not supposed to be able to play multiple characters in the same universe.

And why can't they? @_@ 
If they're good actors and want to do it - let them. There's no rule where they can't play different characters from the same universe.

" And why can't they? @_@  If they're good actors and want to do it - let them. There's no rule where they can't play different characters from the same universe. "

Okay first of all the Blade movies while made by Marvel are owned by a different company, so that means they aren't in the same universe. You won't ever see a Blade vs Punisher crossover anytime soon. Same goes with Deadpool, the character is owned by Marvel, but FOX studios has the rights... that's why Wolverine won't be making any appearances in Thor or Iron-Man 2.  
 
The X-men franchise, Spider-man franchise, Fantastic Four franchise, Daredevil franchise, Punisher franchise, Ghost rider franchise, and Blade franchise, all belong to the company that distributed them. Iron-man, Thor, Captain America, and anyone else, is owned by Marvel still and have the ability to crossover.
 
So as long as an actor plays a character in a universe that won't crossover with another universe with a character they played, then I see no harm in playing him more then one character.
 
Also Ray Stevenson has reported that he will be wearing a fat suit for Volstagg, so I guarantee he won't look anything like the Punisher.

Ryan Reynolds isn't going to play flash. They should have cast him as flash but they can't now. A Justice League movie is what thye want to do. Obviously he can't play both.

Precise was closer to what I meant than any. I didn't include the production companies because I don't think they should matter in this situation. It's one thing to have them appear in the same movie played by the same actor but it is a different thing to watch Blade: Trinity and see Hannibal King and then go watch X-Men Origins: Wolverine and see Ryan Reynolds and then you're like: "Hey it's Hannibal King!" Remember: Kids watch these movies too and they don't understand all the stuff that we do. When they see Ryan Reynolds, they see Hannibal King, Deadpool, and Hal Jordan. They can get confused. I'm sure some kids were confused when they saw Halle Berry and assumed it was Storm or Catwoman or both.
 
Not to mention the fact that when different actors play the same character, it confuses children. When I saw Batman Forever, I was confused as to why Bruce Wayne was a different person. But then again, I was a lot younger than I am now.