Question: If you post a question, Stack Exchange with all their clever AI produces a list under your title called "Questions that may already have your answer". This makes a lot of sense for Stack Overflow, where duplicate questions are to be avoided. It makes a lot less sense for Code Review, where the fiftieth "Tic Tac Toe in Python" is as welcome, and deserves bespoke review, as the first.

While there may be some advantage to some users who click through a few of them and learn a few tricks about their problem or asking a good question, I suspect that on balance it causes more confusion and leads instead to users either not posting at all, or posting not-an-answer answers to and resurrecting long dead threads.

Answer: 
Unfortunately, this is not something we can support or special-case, at least not in the foreseeable future.

As most of you are aware, Code Review is a bit of a special site; questions are not asked for the same purpose here that questions are asked on most other Stack Exchange sites, nor are they held to the same expectations as questions asked elsewhere. In some cases, [it is feasible](https://codereview.meta.stackexchange.com/questions/9038/code-review-questions-must-contain-code) to adjust the software to meet Code Review's unique needs, as those needs are already fairly close to what is needed elsewhere... 

But this site is unusual in its lack of duplicates, and may be completely unique in not being particularly bothered by that. As such, we've no support at all for disabling this feature, and adding such support would introduce fragility. Best-case, it makes for an inconsistent experience across Stack Exchange sites; worst-case, it gets broken accidentally because no one thinks to test it. Neither are great outcomes.

Finally, as you noted there may be some utility to this feature, even here. In addition to being able to learn from others' work, showing similar titles may provide some additional motivation to... Pick a more unique or descriptive title.
As you said, it does not make sense to close them as a duplicate as they should be just as welcome, not only because the code may be a little different, but also that conventions may (READ: will) change over time.

As @SimonForsberg said, it would make sense to change its purpose, but with the new name, it would not make much sense as a flag. Hence it would make sense to disable it.

Or, even better, we could leave it there, but it would not visually do anything. However, it would end up letting the system know that they are related questions.