Hello Medievall...
It does not seem so.. And yes, you understand correctly
I tried to find a command that would enable me to do it on a switch, and I couldn't... And as I said, what would be the purpose?
The switchport is nothing more than that... It does not provide any service to users, it just sends and receives packets, based on what is happening in the switching fabric... So there is no point in assigning it more than one MAC address.
The use of multiple MAC addresses on a physical ethernet interface would only make sense on a server, in the scenario I mentioned in my previous post.
Hope this helps