Both Donny Most an Erin Moran appeared on the love boat at the same time

Both Donny Most an Erin Moran appeared on the love boat at the same time
I think it was a practice for casting sometimes to get 2 from one show to guest on the Love Boat.

As I recall, there was an Episode Where Joyce DeWitt (Janet 3s Company) and Richard Kline (Larry 3s company) appeared together in that same episode, but not in the same story line.

Both Erin Moran and Donny Most Were Guest Stars on The Love Boat Together