Watching Columbo reruns I noticed that a lot of actors have repeat performances in different episodes portraying different characters. This page has a big list of such actors, one of them played as many as 19 different roles. It's slightly distracting seeing the same actor again in a different role.
Why did they reuse actors instead of casting new people to fill the roles? Surely it wouldn't have been hard to find more than enough eager actors in Hollywood.
BCdotWEB hit the nail on the head. The director knows exactly what the actor is capable of, which means you probably spend less time auditioning and more time filming. (Admittedly, I have no source to support this.)
Plus, tt's not just Columbo.
The TV Trope entry for You Look Familiar lists loads of shows that reused actors in different roles, so it's obviously common practice in the industry.
Speculation alert: There may be financial reasons for reusing actors too (i.e. the actors were contacted to the production company that made Columbo meaning that they had to be used), but I need to do some more digging...
