[LockedBreech]

Pretty common. The two most common reasons are:

The department adopted a new sidearm for all officers, but officers carrying the old one were grandfathered in.

OR

The department has a policy which allows officers to select a weapon from a limited range of quality manufacturers within a range of calibers, as long as they qualify.

For example, two officers of my local PD that came to my door last month when a bunch of kids keyed some cars on my street had different guns. Oddly enough, it was the opposite of the usual older officer with the 1911. The sergeant, late thirties or early forties, had a Generation 3 Glock G22 and the young, early twenties officer had a Kimber Stainless TLE. I asked them about it, and apparently my local department is the second type I mentioned above - .40 or .45 caliber are allowed, from a wide range of manufacturers. The sergeant said before the G22 .40 he packed around his own HK USP .45.