I tried to login to Discord. It detected a novel browser or location. Sure, this stuff can happen. It wanted to confirm that I was still me and asked me for my e-mail address. I gave it and it said "This e-mail address is already registered". What. Of course it is. It's me. Mine. The one I have registered with you.
Since I have a few useful things tied to Discord, I felt my pulse go up. I googled for answers, found a Reddit thread with this specific problem. They said "Hey, if you use Gmail you can use the dots-are-ignored-feature to give Discord a "new" mail that will still go to you, allowing you to verify it!" (https://www.reddit.com/r/discordapp/comments/12makhd/verify_...)
Sounded clever so I gave it a fore.name.sur.name@gmail.com variant.
Sure enough, I got the mail.
I logged in. I gasped as I realized Discord had now created a new, empty user for me! It somehow thought I was a brand new user despite this was only a user account _verification_ due to changed IP or whatever to begin with.
I tried logging in to my original account once more and now I somehow got in! The verification on my new account had somehow triggered (cookie? I have no idea) that I was trustworthy again. Phew! I promptly deleted the new-account-going-to-same-mail and breathed normally again...