My opinion is that there is a lot of misnaming going on. M. Digitata and M. samarensis are very similar and I think you need to look at the growth of a mature colony rather than a frag in order to distinguish between the two without examining the skeleton under a microscope. Regardless of what it is anything that looks like that is called a M. Digitata because ORA distributes what they call M. digitata. They don't distribute an M. samarensis as far as I can tell. Since it is likely that the frag's lineage can be traced to them or another similar supplier that sells M. digitata it is simply called a digitata for better or for worse.
Same is true for M. capricornis. The picture of this coral in Vernon's book looks nothing like the multiple tiered caps we have in our tanks.
http://www.reeftalk.com/reviews/data/9/2capricornis.jpg
I suspect we have another type of plating monti but the identification of M. capricornis is what stuck.