You're right, I for example watched all 69 columbo episodes, some several times, and never watched this earlier version of the first episode, guessing I should when I have some time.

Eventually got around to giving a look at this pre-columbo episode and I found it quite interesting since I see it's quite similar to prescription murder, it took me a while to figure out columbo's look was much different than the one I'm used to!

I also noticed some differences in the episode, for example the strangulation is successful, they don't go to the hospital to see the victim, and later on columbo talks directly to flemming's friend about his sus-picions (the - is required to avoid censorship), unlike in the version I'm used to watch, and also some differences when columbo almost catches flemming with miss hudson, they're not drinking in this version before he comes, and in the phone call flemming gives away who it was that called by saying her surname, while in prescription murder columbo just assumes it was a woman, but he didn't know who it was immediately.

Overall I liked it, and I think, as someone who had watched all episodes, it can't be a bad thing to see a slightly different version of an episode, I will have to watch it more throughly when I have time, still some parts I missed cause of lack of time, and as I'm not english and I'm one who wants to understand every single word, it takes me a bit more than it would for a mother tongue person to watch it fully.