Nope, haven't tried it - but assuming the absorption spectra of the dye you're using matches the diode's output... you should be fine.
AFAIK you'll have to combine the 2/3 beams, before you pump your media, though, or you'll get multiple emissions, and not a summed output. Unless, well, that's what you want.
TBH I would be very interested to see if you lase at different L, or observe any interference with more than one emitter going into the same cell (I found temperature and dye stability dramatically changed my output characteristics, both would be altered when struck by the first pump).