What are the consequences of using mismatched power tubes?

Hi all, I’ve got a Mesa Fillmore with bad power tubes, and I’ve got some new tubes on the way. However, I do have two random 6L6s, one is a GS and one is something else. One Ruby, one Tung Sol. They look different on the inside as well.

What are the actual consequences, if any, to having those in my amp for a week or so? Does a mismatched power tube pair stress any components in the amp, or just the tubes themselves? I really don’t care if they wear twice as fast for a week, since they’re already a mismatched pair and I probably won’t leave them in any amp long term.