Gewirth/Kant Universality

Gewirth says that collective universality is "all of us together" and distributive is "each of us separately". Kant says that distributive universality is "to do to others anything that does not in itself diminish what is theirs". What I would like to know is how Gewirth's distributive universality can reconcile with Kant's? I would have thought that collective universality is equal to impartiality but Kant's distributive universality appears to be impartial. I feel like I'm missing some fundamental understanding so if anyone could offer me some guidance I would be very grateful.