The USS Enterprise played the USS Constellation, the Potemkin, the Lexington, the Hood, and the Excalibur.
Does that count?
Kevin
Actually, the Constellation doesn't count since during the times we saw it on screen, it was the trashed AMT kit and not a reused Enterprise shot. Footage of the Enterprise was used for Lexington, Potemkin, Hood and Excalibur in The Ultimate Computer, Exeter in Omega Glory (they did a double shot with it in orbit of a planet) and the Defiant in "The Tholian Web". But, if we are counting ship appearances, the trashed Constellation model doubled for the shot to hell Excalibur in "The Ultimate Computer" after the M5 essentially killed it.
Space station K-7 also appeared in "The Ultimate Computer" even if they didn't call it that. Probably the worst acting job by a ship model was the Tholian cruiser being turned into the Space Yacht Aurora, just by turning it backwards and sticking nacelles on it.
Getting back to actors though:
Ian Wolfe played Septimus in "Bread and Circuses" and Mr. Atoz (and his duplicates) in "All Our Yesterdays"
Edward Madden played an un-named geologist/ Enterprise landing party crewman in "The Cage" (you see him firing a laser pistol from a semi-crouched position at the Talosian mountain elevator after Pike gets taken) and geological technician Fisher in "The Enemy Within".
William Shatner did the double role himself as he of course played Captain Kirk (I won't necessarily count the Kirk double appearances) and a deceased Sam Kirk on Deneva in "Operation Annihlate" (it was Shatner when Sam's body got rolled over to reveal a closeup of his face).
As for the TV announcer in "Bread and Circuses"... IMDb credits him as Bart La Rue and he had no less than SIX episodes that he either appeared in or did voiceover work for (or both). So in addition to Bread and Circuses, he also was:
Nazi newscaster in "Patterns of Force"
Trellane's Father in "Squire of Gothos"
The Guardian of Forever in "City on the Edge of Forever"
Provider #1 in "Gamesters of Triskellion" (50 Quatloos if it was the red one)
the voice of the Excaliban Yarnek in "The Savage Curtain"
Barbara Babcock's character name in "Plato's Stepchildren" was Philana. She also did a lot of voiceovers as well as she was Trellane's mother in "Squire of Gothos", Commander Loskene in "The Tholian Web", and Gary Seven's Beta 5 computer in "Assignment Earth".
And, did you know that the Dos Equis "Most Interesting Man in the World" actor Johnathan Goldsmith also had an uncredited role as an engineering redshirt in "The Corbomite Manuever"? That makes HIM "The Most Interesting Man in Starfleet".
Seriously:
http://io9.com/5951561/the-most-int...d-played-a-red-shirt-on-star-trekand-survived