Wondering if the original ticket number (ten digits starting with the three digit airline specific code) changes if your flight is changed and if so, under what circumstances?

For example, we were on the AA codeshare flight number of BA115 LHR-JFK. That flight was cancelled weeks before we were due to travel and we were rebooked on the AA codeshare number of BA113 later the same day. Will the ticket number we originally received for BA115 (AA-numbered) still have remained the same?