Lots of people abuse other lot types to do this. If you have Get to Work, Dine Out, or Cats and Dogs, you can buy a second house as a retail store, restaurant, or vet clinic and then just never open it for business. The only annoying thing is that every time you edit it in Build/Buy you get a nag message about "YOUR VENUE IS INCOMPLETE!!!!!11!" and you have to say, "Yes, really save without a cash register, good grief." 
Or you can hide a cash register under a roof piece so it'll shut up.
That said, I would also love to buy a second house as a second house and not a fake business.
I hope that helps!
