The episode you're thinking of is "The Greenhouse Jungle". He played Wilson in both episodes, but in one his first name was John & in the other it was Freddie. I doubt they were trying to create a sidekick for him. Sgt Kramer was in more episodes than Wilson. But the Wilson character was a wide eyed fresh out of school kid with training in all the modern methods. Of course, all his technology didn't equal Columbo's brain power. It was this juxtaposition of modern technology vs old fashioned deduction that made these episodes so entertaining & why the character of Wilson was used.
I'm sure someone else knows the character/actor's name, but I always smile when I recall how getting a young assistant for Columbo was met with excuses and delays . . . and finally Dog entered the picture.
The actors name is Bob Dishy. Cigargeorge makes some good points. The character did seem to be written in because he was familiar with the modern methods and technology while Columbo wasn't. In the episode Last Salute to the Commodore Columbo was assigned another young protege named Mac. Not really sure what his purpose was but it was a quirky episode anyway