Hi @TTodd1
Probably the easiest to scale and maintain solution to this is create a primary contact property that is somehow set to indentify the first or preferred contact at an address for mailing purposes.
HubSpot list cant return you just one contact from each mailing address automatically, and you don’t want to have to manually pick the right contacts each time, so it will save you time later to capture this explicitally in HubSpot.
A custom ‘primary contact’ single checkbox property would be enough to store the data, and it could be set manually at contact creation. You could also bulk set it for existing contacts if you do export the data to excel and dedupe there.
Hope this helps.