They do this all the time they call me Sherlock or Sapina or the crying troll. These stupid Anonymous trolls are always bullying me. I keep reporting but they keep coming back with the same answer. It was annoying me so bad I just quit I only been on YA for a month. They don't stop and wonder why they always get reported. They think I been on there for years making up thousands of questions with multiple accounts but it's not true. They don't get of what part I'm new to Yahoo. I've told them a billion times everyday also there's this user who always has to comment on and ruin the perfect answer by calling me an OP saying the same thing. Why did Yahoo get so mean ? 
When you're on a site on a regular basis, you start to pick up on the nuances of language. People tend to format their sentences a certain way and use similar-style language across all their questions. There are countless members I could identify here just by looking at their content- without seeing an avatar or screen name. If you stuck around a while, you may get there too.
Adding to this, people who are regulars on a site tend to set their own standards for acceptable behavior. So, while the site may have specific policies, the members, as a whole, will generally set additional standards. One example of this I see here is that the community doesn't like questions that seem repetitive to them. We have a few members who have a narrow focus about what they'll talk about. Those people aren't breaking the policies even though they can be repetitive, so no moderation action will be taken. However, the community does make note of it and sometimes the answers they give aren't as friendly as we'd like them to be. Someone who is socially aware will generally pick up on this and change course to appease the community, but not all people are socially aware and some simply don't care what standards the community has set. You'll see the phenomenon on every social site.
This in mind, whoever ran those accounts mentioned in your post violated the community standards and, as such, the members are expressing their disapproval.
The problem with being online is, you can't ever really tell who is behind the keyboard. So, while you can often guess based upon someone's language and topic choices, you can never be 100% certain. Obviously, that community seems to agree that you have enough similar traits with other accounts that you must be the person behind those accounts. You may never be able to prove to them you aren't that person.
If you're serious about challenging it, offer to do a video chat with some of the people calling you out. They can either show up and see who you are or continue on, but at that point, you've already demonstrated you've got nothing to hide. Most will back off just because you've made the offer.
I'd rather not comment on the moderation of other sites and behavior of their members, but that's what's going on and one way to solve it if you want to do it on your own.
Randy D 