What I would do when someone changes their usernames is to see if their signature hasn't changed. I was able to tell Bad Dragon was Fatality Ninja due to her signature (the Colossal Titan picture gave her away), so I could definitely say that it helps to at least have a signature for identification, but just as long as there are not any plans to change it.
Just some advice I want to share.
"Where we are, there’s daggers in men’s smiles."
KR Series Finished: Kuuga, Agito, Ryuki, Faiz, Blade, OOO, Fourze, Wizard