Can't see why there would be any problem here. As Denny says, just can't know ahead of time which yeast will be more dominant. I've purposely pitched two yeasts into batches with the goal of getting a blend of yeast character or possibly "toning down" a yeast with more pronounced character. Granted when I've done this it's been blind - just guessing at what the end result might be as far as attenuation, final flavor, etc. Haven't been unhappy with the results. I made good beer.