Host1 and host2 might get both streams - it is the NIC/OS job to do the final filtering.
Moreover, you don't even need multicast MACs collision to get extra traffic - as switches use hash of these addresses (many popular ones are VERY limited - e.g. I'm using D-Link devices and they apparently use ony 4 bits, every 32nd multicast group is received!) the real ...
From IPv4 Multicast Address Space Registry
Extensions for IP Multicasting [RFC1112] specifies the extensions
required of a host implementation of the Internet Protocol (IP) to
support multicasting. The multicast addresses are in the range
184.108.40.206 through 220.127.116.11. Address assignments are listed below.
The range of addresses between 18.104.22.168 and ...