Different Puppies Together In Same Home

We have a 11 week Great mountain Swiss dog and a 10 week Cavalier King Charles. They are both puppies from different breeders and we are wondering if they can play and be together? I'm concerned because they both have not finished their shots. Please advise.

I cannot tell from your question how long you have had each one.  At least so far as big worries as long as they both feel okay playing it is okay.  With bacterial and viral disease a puppy is not "contagious" until symptoms appear.  With parasites this is not necessarily true but also parasites do not pose an acute risk.  If your puppies came with records of previous parasite checks or control then that is reassuring, also try to reduce contact with each other's stool.  Be sure to have both puppies examined and fecal tests within the next few days.