Two TiVo peanut remotes, two UIRT's, one works different

I have two series II TiVo "peanut" remotes - these are the ones with the 1/2 switch. I also have two USB UIRT's. For one remote, on both UIRT's, the volume up/down repeat is detected when I hold the button down. For the other remote, on both UIRT's, it's only detected once. The two remotes are both for Series II TiVo's, they can't be off by that much I wouldn't think. Anything I can try or is it just subtle component differences?
Thanks
Rob
Thanks
Rob