homepod shows up twice in speaker menu on imac

I just bought a couple of homepods to replace my previous wireless speakers. In the course of setting them up with my iPhone, I managed to get them to act as a stereo pair. Voice commands via Siri work well with the two homepods and the sound is quite good from the stereo pair. This leads up to the next question. On our family iMac, the two homepods show up as separate outputs, in this case "left" and "right" which reflect my clever naming system showing which side of the living room they reside. I am curious if it is possible to redirect sound to the homepods as a stereo pair from the iMac. If so, how would I go about doing so? Thanks for help in advance.