I have a number of pair of guns that differ in calibers. It saves on holsters. Lets see some.
A triplelock and a 1950 target or pre model 24.


A model 27-2 and a 29-2, both with 5" barrels.


A model 25-5 and a 24-3


Colt single action armys in .45 colt and .44 special


Rugers, a 1959 .22lr single six and a single six in .32 H&R mag.


Colt troopers in .22lr and .38 special.


Browning 92 in .44 mag and a puma 92 in .357 mag.

As far as identical models differing only in chamberings, here's a Marlin 1894 FG and PG, .41 and .44 Mag.


There's also Ithaca 37 shotguns, a 1952 version in 16 gauge and a 1953 model in 12 gauge, which belonged to my Grandfather. Pic coming soon.

Colt 1911's, with the Delta being a 10mm and the Series 70 repro in .45 ACP. Pretty close to identical.


Then there are the Glock 34 and 35 Practical / Tactical models, in 9mm and .40. No pic, as who needs to see a pic of a pair of Glocks.

Remington 700 LSS' in left hand variant. Timney triggers in both, Leupold bases and rings, only difference is scopes. .300 Ultra Mag wears a Leupold Vari-X III, and the .30-06 now wears a Zeiss Conquest, though it had a cheap Nikon when this pic was taken. The '06 has also lost the hard plastic buttplate pictured, and had a nice Pachmyr pad fit for more comfy blasting. Both are extremely accurate.

Feralmerril-Nice group of guns there!
Ed