I'm going to say something else.
The name "Regan" translates to "Little king" and is a "unisex" name. (Both genders)
As a Regan myself, please do not call other Regan's Reagan
, it is very annoying and frustrating D:<
(Unless that Regan is annoying, then feel free to do so.)
I would talk more about Regan's, but I would be bias, if you do know a Regan respect them. (And don't call them Reagan)