The issue of closing a Question as a duplicate when it amounts to a special case of an earlier Question has come up before. Often the topic is broached on Meta Math.SE when there is a doubt about the correctness of such marking.
In this instance you got a good Answer and were able to learn something from that as well as the proposed duplicate. A Comment spells out the steps needed to connect the more general "Euclid's lemma" (which certainly takes liberties with Euclid's name) to the problem you asked for help with. Or at least I was able to learn something...
The policy on Math.SE takes "exact duplicate" more literally than most SE Communities I participate in. The preponderance of sites use the criterion of whether a proposed Question "can be answered" by the (good) Answers of a pre-existing Question.
To avoid a proliferation of minor variations on a problem type, the notion of abstract duplicates and a List of Generalizations of Common Questions was adopted here fairly early in the life of Math.SE. These mechanisms continue to enjoy fairly robust extensions.
A highly upvoted feature request would have provided a "hierarchy of duplicates", but this probably could only make sense for a subject as highly structured as mathematics. So we make do with the simple linking together of closed-as-duplicates.
Finally I don't think you need to do anything with your Question, and I think it and the Answer by Mike Daas are quality contributions to the site. Of course others may feel otherwise, and theirs is the privilege to vote accordingly.