It has nothing to do with using multiple accounts.
The staff that banned me dragged my account to check if I was using a macro, I moved back to the conveyor belts to show that all the inputs were being done manually.

They would give you a warning, if it were “using multiple accounts.”
They don’t give warnings when they see you hacking. In this case, they thought it was impossible to control 3 devices at once, without the use of any software to aid you.

The only time they don’t allow you to use multiple accounts is when you boost pk or spar with a friend or by using a vpn on the other account, so the stats will count. I’ve never heard of farming with multiple accounts being classified as cheating, especially when there are no hacks involved.