*snip*
I've read somewhere, anyone can allow using the same 1 identity (ID card or passport) to create another account in the same exchange. the register just makes a different phone number but I forget where. I think the exchange that creates this rule is to get a massive new member.
I wouldn't consider doing that, that is very risky and might lead to closing on both accounts, 1 account is equals to 1 KYC since if the system managed to see a duplicate it will close the account automatically I don't think if you know how KYC works. There's a KYC so people would not be allowed to have multiple accounts and to avoid money laundering and system abuse. That exchange probably doesn't check manually and all in automatic.