No, only if the two motors have same design (windings, turns...), which is generally not the case with two motor of the same weight, but it's the case with the 2 different Castle motors.
For example if you try to run on 4S a neu 1515/2Y at the same speed (assuming racing speed on a track for 1/8scale) than a neu 1515/1Y, the 1515/2Y will draw a lot more current because of its bad efficiency. It's because the 1515/2Y "wants" draw the same power than the 1Y with its thinner windings wires (because both motors have the same weight). Dunno if it's clear...