How do speakers get their IP address and host name?
Usually when a speaker is connected to the network it will claim an IP address, basically makes one up, it will also request the DHCP service on the network to provide an IP address. These addresses could be IPv4, IPv6 or both.
However when the speakers are connected directly to a PC or Mac, even with a switch in between, there is no DHCP service to provide IP addresses and the network has to rely on the other address the speaker assigned to itself.
These 'self assigned' addresses are found through a protocol called "Address Resolution Protocol", depending on the OS the implementation of scanning/resolving ARP can differ and may not give the same results (probably wont report incorrect address but rather 1 could be slower than another for example).
The last step for the computer is to figure out which host name (8c-xxxx and 8c-xxxx.local are host names) belongs to which IP address, this is is done through MDNS.