I have a collection of black powder revolvers. Calibers are .31, .36, .44, and I have more than one in each because there are numerous models and manufacturers of these types of guns.
I have also two .22 rifles (a lever action and semiauto) as I inherited one of them, plus a semiauto .22 pistol.
I have a lever action in .44-40 and another in .44 Magnum. These are of course, different rounds entirely, even though they're both ".44" caliber.