I know that I did not manually post such a comment. I did post a different comment related to duplicate closure:
I closed this as a duplicate since this seems to be basically the same as the other question, albeit yours is much more fleshed out. If it's not you can edit to clarify the difference(s).
In fact, my Network Profile shows this comment right next to the other comment that I did not make:
Realizing that the comment that I didn't make looks exactly like the standard auto-comment generated by a duplicate close vote, I figured that perhaps a gold badge closure generates the comment as well, even though it effects the closure immediately. Perusing through Meta, I found these two posts that indeed show that gold badge closures generate and immediately delete the automatic comment.
When comments are deleted they no longer show up in your comment history. Indeed, if I go to my comment history for that specific site the comment does not appear:
Yet as shown above, the comment still appears in my Network Profile.
Further Meta perusal revealed that the issue of a Network Profile showing deleted comments has been raised before. However, that question is status-completed yet the answer there blames it on a problem with the moderator purging comments function, which is not applicable here. Thus, this may be a different bug, or at least a new iteration of that bug which would need to be fixed again.