Correct.
Case in point: I once bred Screamer to two different studs at the same time: Gr Ch Sparky and Ch Stormbringer.
I knew that the ONLY color dog Sparky could throw was black/black nose, because he was a pure, black/black dominant dog. Every pup in every litter he ever threw was black.
By contrast, Stormbringer was a recessive red/rednose and so the ONLY colors I could get from him and Screamer would either be red/rednoses (if Screamer passed her recessive rednose genes) or buckskin (if she passed her dominant buckskin/black nose genes).
Because of the antagonism of the semen, there was only ONE pup, Vise-Grip's Pantera, and because she came out black/black nose there was NO DOUBT that she was sired by Gr Ch Sparky.
Jack