You sign up for two group rides that overlap so that you can get a very long group ride in.
You start out with your personal jersey.
When RIDE A is about to begin, you are taken to the starting are and now are wearing RIDE A’s jersey. During the ride, you are correctly wearing RIDE A’s jersey.
When RIDE B is about to begin, you are taken from your current ride and transported to the starting line and are now wearing RIDE B’s jersey.
RIDE B starts and you are now correctly riding with RIDE B’s jersey.
However, in the middle of RIDE B, when the RIDE A group ends, you are now wearing your PERSONAL jersey, despite there being time left in RIDE B.