In the 1980-1981 overview episode of our most recent season, we talked a bit about two midseason programs on CBS. To be fair, many shows ended up as "midseason" debuts of sorts because of the writer strike we discussed, but this pair of sitcoms wasn't even in the "waiting in the wings" section of that season's TV Guide Fall Preview.
Here is a vintage promo for the shows:
Each premiered April 6, 1981, but while Benjamin had some modest success, earning an Emmy for co-star Eileen Brennan and lasting parts of 3 seasons, Peter Cook's Two of Us was canceled a year later despite being retooled to add Tim Thomerson when it made the Fall 1981 schedule.
Here is a promo for the premieres of the two shows: