I have the same issue, I have two mini homepods in two homes, and they mess around with each other when a standby homepod in the second home takes over as the connected home hub. For example if the home hub is in a different location (i.e. the second home) eve temperature sensors will not be able to retrieve temperature readings. The Eve devices go into a "not responding" status until you force the connected homepod to change by turning off the connected homepod in the second location. The homepod mini in the primary location will then take over again. It's a real pain, as in this example the temp sensors control the air con, so if the homepod mini in the second home takes over, then the air con plays up because the automations (dampers) don't get triggered.
The only way around this with certainty seems to be using a second apple id. Oh no. I suppose if you use family sharing with a second id you don't have to buy new subscriptions if for instance you want to play music from your apple music subscription. I read another post that a person used MAC filtering for the homepods as his two homes were connnected by a VPN. I looked at this and found the standby/connected status in controlled over the internet connection and not direct between homepods on the same LAN so that option doesn't seem to work. Be handy to have the same functionality as the apple tv where you can disable homekit for individual homes.
