I'm fairly sure the default diopter power for all Nikon viewfinders since the F is designed to be a -1. Most bodies sold with a screw-in eyepiece which were just plain glass and didn't change the diopter strength. If the eyepiece doesn't have any markings on the edge, it's just glass. The mark on the diopter is the final effective diopter of your viewfinder when it's installed. So, your +1 diopter is actually a change of 2, from -1 to +1. I use an +0.5 diopter, since I wear reading glasses with a +1.5 power.
The diopters (marked on the edge) are supposed to replace the plain eyepiece. No reason to stack one on top of the other, unless you like it that way.
I've had almost every manual-focus Nikon body and many of the Nikkormats, and have used the same power diopter on all of them.