For years, I was thinking that once the celebrity versions of Put Down the Duckie and Monster in the Mirror were introduced that they stopped showing the original versions without celebrities. But looking at "what links here" on the Muppet Wiki, I see that the non-celebrity version of Put Down the Duckie was sometimes shown in the 1990s*. In fact, there's at least two episodes where it followed the sketch with Ellen DeGeneres and Elmo listening to headphones, and in both cases it was the non-celebrity version.
Of course I haven't gotten around to checking on whether the non-celebrity version of Monster in the Mirror ever aired past season 22.
I've seen that, currently, the earliest-known appearances of both the original and the first celebrity edits of Put Down the Duckie are season 20 episodes, with no known first appearance yet. I wonder if Sesame Street, Special was the first appearance of the celebrity version. It's the first time I remember seeing that version, and it aired around the times of season 19 and 20 (I think Muppet Wiki does have a date listed, I think Spring 1988, but I'm not real sure). Makes me wonder, if a segment first appeared in a special or home video, would the scripts list those as the first appearance, the first actual episode after premiering in a special, or just not list a first appearance at all (at least with Big Bird's Birthday and The Street We Live On, those were shown as regular episodes, in addition to being specials, and have episode number designations)?
And wow, the original celebrity version of Put Down the Duckie wasn't on the show for very long. It could have first aired in season 19, but Muppet Wiki currently only lists season 20 and 21 episodes with it, and it didn't air at all in seasons 22 or 23 (unless it's part of any of those few episodes where they couldn't make a full guide), then in season 24 the new celebrity version premiered, and it seems the original non-celebrity version didn't air either during seasons 22 and 23. But the first celebrity version happens to be the one that's been released on home video, continuing the exposure (as far as I know they didn't replace the celebrity version when Sesame Street, Special was released on home video, despite making other changes).
*I actually didn't see Put Down the Duckie in new episodes often in the late 1990s, in fact most times that I did I had to leave the room or whatever shortly after it started, as I was unaware for years of the fact that they eventually changed the celebrities, and didn't know it was the non-celebrity version in a season 30 episode for years.