Beaugregory Damselfish And 75 Gallon Tank

[gotteeguy]

What is the difference between a beaugregory damselfish and cocoa damselfish, especially when both species are juveniles? Are they even two different species, or are beaugregory damselfish just the dominant male cocoa damselfish?

Also, how many slippery dick wrasse and beaugregory damselfish can live in a 75 gallon tank together?
I can hardly find any information on beaugregory damselfish.