Hello Abdulrahman
The “issue” of having multiple IP addresses mapped to the same MAC address is not something that has been solved, as you put it, but something that exists and should be taken into account by network engineers. By using only specific multicast addresses, engineers can steer clear of addresses that may map to the same MAC address.
Even if an engineer is unaware, it is unlikely that you will have multiple multicast IP addresses mapping to a single MAC address. Not impossible, but unlikely. If this does take place, multicast will still function correctly. As a multicast client decapsulates its received multicast packet, it will see the destination IP address, and will simply discard it if it does not belong to this multicast group. It adds a little overhead, but it doesn’t break the multicast operation.
I hope this has been helpful!
Laz