In the Starcraft 2 community it is called barcoding. Basically, I 1 | l are all accepted characters for a name and I think some do look actually identical on most fonts used in the game. So yeah, one person doing that you call "barcode", 2 persons doing that, you already have deniability. Be more than 10, and that's a crowd.
There was a time where call of duty ghosts was exploitable, and people could wipe/delete the accounts of anyone whose username/gamertag they knew. Streamers and pro players had to use barcode usernames to avoid getting their accounts deleted.
Google's AlphaStar StarCraft bot did just this under different accounts. Along with some other fingerprinting, many of the accounts and replays were found by the SC2 community.
To my knowledge, it played with only one account. It played exactly 50 games with every race. It was outed mainly because of two things: A very high win rate (above 80% IIRC) and the fact that as a zerg it produced units by selecting larvas directly, which no one ever does (someone explains that it uses control groups but they are hidden and dont show up in replays, I dont know how accurate it is)
this goes back at least as far as the original Unreal Tournament, I even saw a player using it in the fairly obscure Shogo: MAD multiplayer community. Never knew why it was done back then, I assumed it was just to be cute, but it did make it troublesome to mention them in ingame chats.
Number plates existed for decades before ASCII was invented. Before computers, people often used mechanical typewriters which didn't have keys for 0 and 1: you typed 0 as O and 1 as l. I threw away one such typewriter recently. It was in good working condition, with its instruction manual. It had been made in a country that no longer exists. You may imagine how sad and nostalgic I felt.
