How many possible IP addresses are there per multicast MAC address

Out of 28 bits in multicast IP address, only 23 are taken out and mapped to MAC addresses. The shortfall of (28-23) i.e. 5 bits => 32 possible multicast IP can map to same MAC addr eg. 224.10.8.5 and 225.138.8.5 both map to 01-00-5e-0a-08-05