Change 1 character. Problem solved.
This is a minor issue with the software design and not an option. But change 1 character.
Suggesti0n of Junior Moderating vs Request to Members
Okay, there does seem to be some time limit. To find an old thread I picked a random word likely to be used in a discussion and searched for threads before a specific date (just plugged in this date in 2005). I picked “Morons who won’t see good films” (a 2005 pit thread) and was able to reuse that title. Does anybody know the time limit? Finding it by trial and error would be tedious and annoying for everyone.
(FWIW I was looking for threads that mentioned movies, not morons…)
I suggest from now on when this happens we add the word ‘corn’ to the title to disambiguate it.
That’s just begging to have the thread cornfielded. 
I think it may be a difference between how discourse changes apostrophes from the changeover to how it changes apostrophes in new threads. In the old one it was omitted in the URL, in the new one it was replaced with a hyphen.
I tested a thread title “Faking to be handicapped and Disneyland”, which has no punctuation, from 15 years ago and it wouldn’t let me create it.
How does one fake being Disneyland?
Someone wanting to make another topic like that could use the title, “Disneyland and faking to be handicapped”
~Max
I just find it rather strange. Sure, it’s easy enough to work-around, but what’s the point of such a limitation?
Anyway, sorry for the hijack!
I presume that it is because the URLs are based on the titles, and you need to have a unique URL for each thread. They could have added an option to add a number at the end or something to disambiguate, but, knowing how “opinionated” Discourse is (@codinghorror’s word, not mine), I suspect there was then some argument about “encouraging people to write unambiguous titles” that was considered more important.
If I had developed it, I would have had Discourse warn the user that said title had already been used before, and to make sure their title was unambiguous. But, if they continued, it would still post, and the URL would add a number to disambiguate. Mods could, if they wanted, choose to get a notification about such, so they could then check and make sure the title is indeed not ambiguous.
Especially since Discourse also encourages closing zombie threads, it just makes sense that a newer thread may warrant the same title as an older one. Thus the resulting impression is that the user is having to workaround a limitation, which can make any software feel unfinished.
Well, it was a rhetorical question, but I basically agree that it is probably a (questionable) design decision that Discourse made in order to facilitate having unique conversations or some such.
The URL pattern, FWIW, appears to be https://boards.straightdope.com/t/{thread-name}/{thread-id}/{optionally-post-number}. So even if the thread name were non-unique, the thread ID would be. Ergo, URL uniqueness doesn’t require unique thread names nor the workaround you propose.
FWIW, I think that Discourse is right not to allow duplicate titles.
It can only lead to confusion, and to replies and links to the wrong topic – and there’s no advantage to allowing duplicate titles, as far as I can see.
If you really MUST start a new thread with a duplicate title, instead of bumping the existing thread on that subject, then add a suffix yourself, ‘Part 2’, or ‘2021’ or something.
In fact, it looks like there’s a Discourse setting for duplicate titles, and you can currently have
- No duplicate titles
- Allow duplicate titles in different categories (probably what’s set here)
- Allow all duplicate titles
Well, this is something like eleventy-billionth on the list of things I care about, but I disagree. I think your concern is probably best addressed with a time-limited (and possibly forum-limited) period of uniqueness, rather than an all-time, all-space limit.
Assuming ‘categories’ means ‘fora’ (I can never remember Discourse’s nomenclature for these things), I think we determined that’s not what’s set here. The block is across all fora. See post 19 by @Darren_Garrison.
To get back on topic of Jr. modding vs. member suggestions:
I can see how minor suggestions to other members that may make them better members of the community may seem just that - minor. But that’s the perception of the person making the suggestion. You never know how that’s going to be received. You minor suggestion, may be their ultimate affront. It’s probably better to just flag the post for follow up by a mod, and let chaos reign until one of them looks at it.
I’ve dropped my protest, mostly because I hadn’t realized that failing to use minimally descriptive thread titles actually is a rule violation and so it does appear a bit more like Junior Moderating than I’d first thought. And also, because the thread title remains unchanged after a lot of Moderator attention. I still think it’s wrong and dumb to allow dippy thread titles in GQ and CS (to a lesser extent) but I’ll grin and bear it.
More broadly though, members make requests to other members pretty frequently and they’re not always nice. ‘Try reading for comprehension’ is one you see a lot. “Point out where I said [this that or the other]” is another.
Get your own thread! 
I think the only solution is for @GreenWyvern and I to get married.
Having a bunch of duplicate titles isn’t just bad for you, it’s bad for SEO, it’s bad for everyone else who wants to find, well… anything.