Horne played Gavin in the penultimate episode of Gavin & Stacey at 10pm on BBC One, and then Catherine Tate's grandson at 10.30pm.
He said on Twitter: "I can only apologise on behalf of the Beeb for this scheduling. Even I’m bored of me."
Other actors to make numerous festive appearances were Larry Lamb (EastEnders, Gavin & Stacey) and Catherine Tate (Doctor Who, Nan's Christmas Carol).
Despite the number of recurring appearances from BBC actors on Christmas Day, the broadcaster still produced 14 out of the 20 most-watched shows, including all of the programmes above.