Some isp bind the pppoe account and mac, so if you have more than one pppoe accounts, you should have more than one mac address.
So for the v7 version, hope it will support:
1)add macvlan interface(add it’s also suit for other situation, eg. when you want to get more than one address from DHCP server)
The better question is … do you have an associated pppoe standard that talks about this requirement. If ISPs are simply applying a recognized standard then you have a leg to stand on in that mikrotik is not following the standard or at least keeping up to date with it. IF there is no such thing and ISPs are doing this ad hoc, then dont expect MT to do anything extra…