I think you could just make up unit/apartment numbers to make your address look different? I know USPS provides an address validation service[0], but it apparently only understands street addresses and not whether there is a single family home there, or a 10,000 unit megacondo
I actually worked on a service for a company in the past that could identify these types of scenarios and determine if they are fake.
There were a number of scenarios to consider (there was a "probability score" involved), but the biggest one is: "How big is the plot of land at address XYZ. Is it in an urban, suburban, or rural area? Is the existing building a house, commercial building, or skyscraper? Does this unit buy products of this type in bulk?"
Easier than you think. Note that the score had hundreds of factors. These were the easiest to consider.
(In most states, you could pull public info and tell right away if an address has multiple legitimate units or not FYI)
I'm curious how you handled addresses that couldn't be validated. From my perspective, that's a big blind spot of real-world implementations of this sort of stuff, and thus the condition under which most of it happens. Not quite "make up a unit number" (freight forwarder red flag, anyway) but pretty close.
If you use the USPS API, it gives you a specific message if it's a multi-unit address:
Default address: The address you entered was found but more information is needed (such as an apartment, suite, or box number) to match to a specific address.
How many people in the same mega-condo are trying to order Raspberry Pis though? Ignoring unit numbers would still probably be worth the small amount of collateral damage.
