John-
I'm new on here and just stumbled across this post tonight.
What you did hear were in fact Montgomery County, Ohio TRS groups. And yes, I know, you were listening to MARCS, not Montgomery County.
I experience a similar anomaly here in Dayton, Ohio, where I live. On my PSR 500 I pickup Montgomery Co. TRS groups as a wildcard hit on MARCS. It happens in a few areas consistently, e.g. Dayton Mall area, I-70/Huber Heights area. I have no clue why this happens, and have spoken to several people that are more advanced than I at scanning and they experience the same issue.
I've never had this happen on my BCD396T in these areas. The only similarity in these areas are that they are high RF environments. There has to be some type of mixing amongst voice channels/control channels or something. Next time through you might make note of exactly where you were when you received all of this.
Only thing I can tell you is.....I know exactly what your speaking of and your not crazy or listening to Montgomery County. If I hear of what has been causing this, I will hop on here and let you know.
Take care,
Jim