Historically, bowyers made non matching grooves. Although these days, some modern bowyers will make matching grooves. The principle is to increase the glueing surface.
In either case, both sets of grooves need to be filled COMPLETELY with glue. So with matching grooves, your wooden core and horn will mesh and the excess warm glue will be squeezed out during glue up. In the case of the non matching grooves, they will not mesh, and the glue will fill all those voids.
There have been no findings of matching grooves before the early 1900s, so this is a modern adaptation. Even now, it is said that it is not necessary to use matching grooves on bows under 70-80 lbs. Supposedly they also keep glue failures from spreading laterally across a limb, potentially avoiding a complete limb failure.