I'm looking for a sci fi series from the 80ies. With a duo escaping to another world and having lot's of adventures - any hint what it s called?

That describes a whole lot of stories in the genre. Sorry, I don't know the one you want.

But "duo"? That has connotations. I suppose if Batman rode his horse across the galaxy it would be called "Batman and Dobbin".

Bill and Ted's Excellent Adventure.

Off hand, the only series I can recall is"Sliders", but I thibnk there were more than two people. 

Could it be Quantum Leap? Scott Bakula as Sam Beckett and Dean Stockwell as Al.