Slavisa Jokanovic will be facing a difficult decision over his goalkeepers, according to former Fulham stopper Richard Lee.
Lee worked with Button during his time at Brentford and with Bettinelli when he moved to Craven Cottage on loan in 2015 and rates both of them highly.
Lee said: “To have two first class goalkeepers is really unusual. It'll be interesting what happens going forward.
“It's a really unusual situation. At some point, something needs to give. Bettinelli has had a fantastic start to his career and knowing him as I do, he'll want to play and not sit on a bench.
“Something will have to give. Marcus and David need to play. They both could be in the England reckoning (in the future).
“It won't work with them being at the same club. Something will need to give and I'm sure that'll happen sooner rather than later.”
Lee rates both goalkeepers highly and believes both of them are of similar characters as he revealed Button turned down moves to Premier League clubs due to the prospect of being first choice at Fulham.
Lee added: “I know he had offers in the Premier League where he may not have played and he chose to go somewhere that he wanted to play.
“Some fans may not understand that but I know he wants to be the best goalkeeper he can be and play as many games as he can.”
On Bettinelli, Lee also said: “Marcus is another very promising goalkeeper. He's a really nice lad as well. It's interesting that he's been linked with a lot of top clubs such as Chelsea.”
Lee understands what Bettinelli is going through as he went through similar during his career, notably at Brentford in 2010, taking the number one role between 2011 and 2012 before being number two to Simon Moore and Button in the final years of his career.
He explained: “It depends on the stage in your career. Someone like Shay Given is a great number two and he can back up someone like Jack Butland. That dynamic works.
“In the last year or two I wasn't where I was when I was younger. I was happy to back up Butts and Jack (Bonham).
“I knew I could help them and be an asset in that manner. I knew if I was thrown in I'd do a decent job but in the long term Butts was always going to be a better choice.
“I had it with Andy Scott bringing Ben Hamer in claiming we had two number ones. Neither of us were happy as we both wanted to play.
“At some point, it'll kick off and he'll need to change the dynamic. If it's going to be Butts then he'll have to be someone who is happy to be a number two.
“It'll be either a young lad looking for experience. But given Fulham's size, it'll probably be a much older keeper who can step in when needed.”