I know that according to Dr. Strangedupe, leaving existing duplicate questions is good for searchability. But what about intentionally asking a duplicate question with different terms?
This comment made me think of that.
No, I do not encourage that. I consider questions posted intentionally as duplicates (e.g. OP writes "I know it's asked before but think it did not get enough attention) as bad practice. Posting duplicate for the sake of searchability is no different or better, in my opinion.
To improve searchability of a question, one can edit the original and add keywords, improve title, etc. No need to intentionally add duplicates to the system.
While I agree with Shadow Wizard's answer, what I meant with my comment was that submitting a question that only turned out a duplicate after you basically finished typing it, maybe even not via the related questions feature, e.g. you didn't know the perfect keyword to search for and only the full description of the problem yields the duplication, it may yet be appropriate to post the question nonetheless. But that should indeed only be done if you honestly believe future visitors will otherwise end up typing yet another full question before finding the dupes, and not for the mere sake of adding keywords.
I'm more of a 'descriptivist' than a 'prescriptivist' when it comes to what we should do on the SE sites.
It's the case that SE site search is bad enough that it's easy to create duplicate questions, even unintentionally. See my inadvertent duplicate of this very question:
It would be ideal to (always) be able to edit a question so that it can serve as its own 'signpost', i.e. to directly improve its searchability.
But improving a question's title may not improve its searchability. It's common for beginners, in anything, to not yet be familiar enough with the terms or jargon of the relevant area to be able to ask a 'good' question. Because of this, I think one should be very careful to NOT remove potentially useful search terms or keywords from a question, even if doing so would overall improve it.
The alternative, that doesn't ever damage searchability, seems to be to just add extra search terms directly to the question itself. That seems like it might be unwieldy in its full generality because of the shear number of possible ways of asking a question.