"If the two races were ever to team up against the illithids" – MToF, pg 85
"The githzerai were born as a race…" – MToF, pg 93, under the heading Githzerai
These two quotes imply that the Githyanki are (lorewise) two separate races. However,
"Long gone are the days when the gith race" – MToF, pg 87, under the heading VLAAKITH’S DILEMMA
Are the Gith one race with two subraces, or two races?
I would prefer 5e sources, that distinctly mention this, but if nothing else is avoidable, then sources from other editions are acceptable.