Is it possible to touch type fast on more than one layouts?

"It's possible. I can type very fast with Dvorak, but also fast with Qwerty.

For me it was never difficult to maintain both layouts. As long as you practice each one every once in a while, you probably won't forget it. Though you might lose some of your speed on the less dominant layout (for example, I still make some mistakes on Qwerty because I use the Dvorak placement)"