Usually when you get a pot of a croton variety that was propagated by cuttings there are three in the pot. There is certainly no reason you couldn't do the same thing with three different varieties. You would need to take into consideration the growth rate of each, light requirements, etc. I have several different varieties growing close together, but not as one plant. For me I would not want to lose the habit of each so give them enough space to showcase the individual plants, but they do grow into each other. To have this work it would all come down to selecting the right varieties. I have never seen them sold like this before or seen them in any of the crotonheads gardens grown like this, but some of the veterans would know better.