I have the table top Rondo, and it only has one speed. Alot of the floor models have two speeds, comes in handy when you're doing miles and miles of puff or croissant dough.
One side should be a bit faster as this "pulls" the dough out of the rollers, if both belts are going at the same speed then the dough might get bunched up behind the rollers.
If you've never cleaned a sheeter, or changed belts on one, they are very simple, albeit complicated machinery-wise. Basically you have a conveyor belt stopping at two s/s rollers, you can adjust the height between the rollers, and you have a belt on the other side of the rollers. The rollers have scrapers riding on them, for if you had any dough stuck on the rollers, it would just pick up more dough on the rollers and make a mess.