No delay. No issue. The reason for the double numbers is that there are only so many numbers. Don't think it happens very often.
Example: UA 900 (probably a CRJ 700) goes SAN-SFO, arriving around noon. UA 900(heavy) flys SFO-FRA, departing around 2pm, but is a 747. No issue.
Perhaps in a previous situation it was considering a connecting flight with a change of planes. Doesn't matter. No issue.