If you're writing an IRC client, don't even try to send multiple WHO commands in parallel. Servers have rate-limiting for these anyways.
Don't waste time hoping for WHOX to solve the issue: at first it looks like it does, but in reality it doesn't. It allows to make the difference between WHOREPLY messages, but ENDOFWHO messages will still be mixed up.
Technically could have a more involved system where *some* WHO commands are allowed in parallel, but it's not worth it.
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