Another Simmer just shared a way to own two lots in another thread. Without mods, by the way. Create a retail lot, even if it is a home, place a desk in a walled off basement area and place a cash register on the desk. Just make sure no one can get to it, and don't open the store/home for retail business. Purchase the 'retail lot' and there you go. Two homes you can own at the same time. I have done this with venues with items I don't really want in the main area. I hide everything in a basement the Sims can't get to, the requirements are met and my venue has only the items I feel the need to have.
