Homepod Eddie, or Homepod Steve, or Homepod Jujuba. For multi HP households, let us name the HPs if this is an issue.
Conceptually, a multi-HP household is going to have HPs in different rooms (support whole home, someday). In this scenario, the nearest HP will be able to hear and process a generic "Hey HomePod"
For the households that pair up 2 HPs in the same room for "stereo like" sound (someday), they are paired to work as if they are one so they both might answer a generic "Hey HomePod" query.
Or again, let us name each of them if we want... like we don't name children all "Bob" or "Steve" so we can get the right one to respond when we want to communicate with one of them.
And I still dare any of us to name a kid or all kids Siri.

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That's fine but the point of frustration of multiple Siri devices responding to "Hey Siri" is what motivated me to offer the idea. That frustration isn't solved by "the future" responses like this. I fully agree that Siri should be plenty smart already and able to do this without ever being confused. But Siri is NOT that. And writing down "the future" won't make Siri that today, tomorrow or the next day/month/(maybe year or years).
That idea is something that could be implemented quickly and "just work" ASAP. Your counter is something that Apple might get around to... someday... or not. Everything can be far better out in "the future" somewhere but we all live in the now. Living with frustrations in hopes of "someday" is one approach. Another is to bridge the gap between now and "the future" with tangible solutions that would work much sooner than that later.