I have had a number of duplicate-chambering rifles over the years, but it used to be worse. At one time had six .30-06's, including two bolt-actions, a lever-action, pump, drilling and single-shot. The two bolts were a NULA and a pre-'64 Model 70, so there really wasn't much duplication of rifle type. But also had four .250 Savages at one point, three of them Savage 99's. Also had three .25-06's for a while, but only briefly.
Right now only have one .30-06 (the NULA), but have three .308 Winchesters, two .270 Winchesters, two .243 Winchesters, two .223 Remingtons, and seven firearms chambered for the .22 Long Rifle, though two are handguns. Oh, and two .25-35's, though one is a 15" handgun barrel for the T/C Contender, and six 12-gauge shotguns.
My worst case of duplication right now might be my pair of .45-70 trapdoor Springfields. But that's mitigated by the fact that one is an original rifle and the other a Harrington & Richardson Officer's Model.
