Did anyone notice in the episode "Star Struck" (where Terri falls for a soap-opera star) that the other man in the restaurant is Wanda X from Season 3's "The Love Diary"? :lol: The actor's name is Paul Barselou.

LOL yeah I noticed that, the show always had a rotating slew of guest actors come back and play a different character both on TC and The Ropers and Three's A Crowd, a few examples:

Jeffrey Tambor - besides his gig as Jeffery P. Brookes III on The Ropers he was also on TC in three epsiodes:
Father Of The Bride (Winston Cromwell III)
Two Flew Over The Cuckoo's Nest (Dr. Tom Miller)
Jack Goes To The Dentist (Dr. Phillip Greene)

Anne Schedeen - known more as Jack's girlfriend Linda in the show, she was in 5 episodes:
Will The Real Jack Tripper... (Linda)
Double Date (Linda)
Stanley's Hotline (Linda)
Honest Jack Tripper (Lisa Page)
Jack Gets His Own Restaurant (Louise Prescott)

Yes, and Ruta Lee was in two episodes, both times as a real estate agent:
-Anniversary Surprise (Ms. Dawson)
-The Matchbreakers (Marsha Whitewood)

Mickey Deems was on lots of times as different characters (he also appeared on The Ropers):
- Extra, Extra (1982) ... Mr. Hubbard
- Mate for Each Other (1982) ... Maitre'd
- Father of the Bride (1981) ... Singing Telegram Man
- A Hundred Dollars a What? (1980) ... Gambel
- Jack in the Flower Shop (1978) ... Mr. Harwood

Sondra Currie appeared three times as Jack's love interests:
- Jack Takes Off (1984) ... Arlene Price
- Janet's Secret (1981) ... Shelley Green
- Alone Together (1977) ... Sherry Lee

And Macon McCalman appeared three times:
- Hearing Is Believing (1983) ... Roland Wood
- Janet's Secret (1981) ... Roland Wood
- The Catered Affair (1979) ... Mr. Penrose

There are a lot more, but these are a few more extras that reappeared over the years.

The practice of having an actor/actress come back multiple times in different roles was very common back in the day, I don't know why for certain but its not like that was a shortage of Hollywood actors was there?

Today with people owning their favorite shows on DVD are now more savvy and can pick out a recurring actor/actress each time.