Since you linked to a Meta question, I'd like you to take a look at JHB's answer.
Essentially, duplication of a question occurs when two questions are similar enough in scope, material and focus that good answers for one question will also be good answers for the other.
- Sometimes duplicates are actual copies. A long time ago someone asked about the feasibility of using boars as cavalry animals. And then recently someone else asked the same question about the feasibility of boars as cavalry animals. Obviously this is a duplicate.
- Sometimes the duplicates ask for the same information, but in a slightly different way. Maybe a question was asked 8 years ago about the nutritional content of blood in the context of vampires. For whatever reason, somebody asking about whether a vampire can survive on a diet of blood didn't find that earlier question. It is clear that the question is not precisely identical; but it is also the case that a break-down of the nutrients found in blood will also answer whether a person can survive on a diet consisting solely of that nutrient profile.
It would be within the community's rights to close these questions.
- Now, for a third kind of duplicate, let's consider another pair. Let's say someone asks how a primitive society can rig up a way of dragging stuff using a sled with ski-runners. Now let's say someone asks how a primitive society can rig up a way of dragging stuff using a travois.
You might think, well, skis slide along the ground while travoy sticks drag one end on the ground: two entirely different kinds of vehicles, therefore no answer to one can possibly be applicable to the other.
Yet, dragging stuff with either vehicle is simply a matter of managing the harness that connects the motive power with the vehicle. The motive power could be a horse, a dog, a person or even a motorised vehicle -- all the same, therefore the questions are duplicates.
So where does this leave your two questions? Obviously, the weresnake question -- Q2 -- is not an exact copy of the werefish question -- Q1. There are two different kinds of creatures after all! Nor do your questions ask for the same information in two different ways.
What's going on in your case, I believe, is that you've got the third kind of duplicate, the one that seems on the surface to not be a duplicate, because two entirely different creatures are being discussed, but in fact are the same fundamental question because the answers for one work with the other. In other words, it doesn't matter which creature you ask about, all the answer apply to both equally well.
I understand that your argument is that none of the answers carry over from one to the other. I've read both questions and all the answers and don't come to that conclusion. This puts the ball back in your court as it falls to you to convince me that these aren't actually the same question.
Your questions are a pair of duplicates simply because they not only ask the same question --- How do I tie up a humanoid person with some kind of animal hindquarters --- but thus far all the answers apply to both questions and many more possibilities besides.
The Missing Link
I suggested before that, just perhaps, you're missing this because you're somehow stuck in the minor details. You seem to be saying that a fish tail and snake tail are so radically different that there is no way whatsoever that one method for tying up can possibly work for both, simply because that one is shaped like a fish and that one is shaped like a snake.
I could be wrong in that assessment! In all of our discussion, you haven't actually pinpointed how the two are "so different in specifics" that "almost no answer works across both questions."
In reading the obracentaur question, I can only hazard at two rationales for closure:
- It is such a trivial question that it really doesn't rise to minimal expectations. Basically, what you're asking there is "what would a mix between a donkey and a zebra look like" and after an agonizing 1.32 seconds of googling, discovered that the answer is a zonkey. Just stick a humanoid torso on a zonkey and you've got your answer.
To be honest, that kind of question is a time waster for this forum. There are hundreds of really excellent questions you could ask about obracentaurs and ono- & zebracentaur cultures, but you didn't! I'm not surprised that it was closed, I'm not surprised that it's gotten a neg. 4 vote and I'm not surprised that no one has voted to reopen.
- The question you asked, about what what a centauroid would "realistically look like" is addressed in the Anatomically Correct Series.
In my opinion, I don't think the specified ACS actually addresses what I think you're asking, so I agree with you that that is probably not the best closure rationale that could have been chosen. It could just as easily have been nominated for closure for being too opinion based or tagged for deletion for being of too low quality.
What's Sauce for the Goose is Sauce for the Scorpion
I voted to close your werescorpion question --- Q3 --- because the same kinds of answers that you got for the other two will apply here as well. This is a duplicate. And not only that, but it's a tiresome duplicate!
And I see you've tried again with a humanoid squidopus --- Q4 --- and that it's been closed. Maybe it's time to stop, take stock of what you're doing wrong and change that behaviour? Especially in light of two really excellent worldbuilding questions that you've asked recently!