I've heard it can be done, but I would not mix the different types of bulbs. I asked a simliar question not long ago because my dual T8 light fixture that I bought siad to use 30W bulbs onthe box. I found some T8 bulbs I liked, but they were only 25W. I pulled the fixture apart to look at the ballast and the sticker said it was for two T12 bulbs! Either 25W or 30 W! So apparently, this is pretty common practice, although I'm not too familair with the T10 size. I'd say as long as the wattage is correct, then it would be ok.
Bill C.