The answer largely depends on whether the meeting organisers were aware of this but perhaps the results had not been updated.
If this was a track meeting, the error should be notified to the organisers by the team manager (if a league) or by you if it’s an open meeting. In the case of leagues, particularly the YDL, the league administrators have to note the changes and will confirm to us when we can update.
If however this was a road race and you gave away and/or were given somebody else's number without the consent of the organiser this is not allowed and can result in the relevant parties being excluded from future events. As such, we cannot condone the practice by changing the results. If we became aware that somebody ran as somebody else we would change that performance to "AN Other" or "Unknown".