This is what I know. could be wrong, though.
The Douglah is a brown 7-Pot. one of several distinctive varieties. in order to achieve the brown color, a 7-Pot was crossed with a brown C. chinense. most likely it was a Congo. there are several different brown 7-Pots, just like there several different red 7-Pots. Douglahs are brown 7-Pots, but not all brown 7-Pots are Douglahs. so no, they're not the same. I also consider the Douglah to be a 7-Pot because it shows consistent qualities that most belong to the 7-Pot. yes, it was crossed. most if not all chiles in Trinidad were crossed at one point. the name Douglah refers directly to the brown color and is part of the local slang. it can't be used to describe a red chile. this will be misleading or just wrong. a red Douglah is a a 7-Pot. obviously a unique strain/variety, but a 7-Pot.
My two cents.