I have two VS65R combos, I want to run them in stereo. Is this possible? I've never tried to do this and don't want to harm them.
What do you mean exactly by "run them in stereo". To be stereo you need something that produces a stereo effect (i.e. has a left and right output).
In this case you just connect the left output to one amp and the right out to another amp.
If you just want your guitar coming out of both then some kind of splitter will be needed to split the guitar signal into 2 and feed the split signal to each amp.
In practice I've found that either of these options are just not worth the effort, but maybe you'll like it.