How do you know? Have you measured a representative sample from both? I'd find it very surprising if the nominal 24mm bearing bore varied outside the usual tolerance range for industrial standard bearing cartridges
I’ve taken a representative sample of them, well worked on quite a few and they have all been the same. I’ve tried to push the bearing on to the axle out of the frame and the NDS goes on ok, but the DS is ever so slightly bigger. I thought it was a well know as none of my colleagues were surprised.
How do you know? Have you measured a representative sample from both? I'd find it very surprising if the nominal 24mm bearing bore varied outside the usual tolerance range for industrial standard bearing cartridges