How oftern does the opposite happen where you have been on the same aircraft with a different flight number going where you need to go? I haven't had this happen to me but plenty of same flight number having to change to a different aircraft.
While back, if you were flying from LAX to DTW via MSP on the 8 AMish departure, you could be on the same 753 but that's gone now. The crew that were on these flights stayed on to go back home to LAX from DTW. These all had different flight numbers but same aircraft.

HJ