I took USMLE Step 1 but not Step 2. All my other tests are COMLEX. In general, I've found that the ~10 programs I've interviewed with, none require the USMLE. However, one institution I interviewed at hasn't taken a DO in the past 30 residents over 8 years. The PD there even asked me how to interpret the COMLEX scores for her because she didn't understand them. Then she asked me to take the USMLE Step 2 so she can better compare my scores.
Certainly not common but, there are some programs. Sorry, no disclosures until I match.