My wife and I have been carrying two mortgages, intentionally, since April. We live in a low cost area so it's really no big deal, both mortgages come out to less than half of what it would be if we lived closer to a city center. One of them is our primary residence, and it only has five years remaining on a 10 year amortization. The second we bought because of its income potential and nothing more. The company that my wife works for, a federal nationwide entity, is now our renter. They rent a portion of the space to run their local operation. As such they subsidize the mortgage, cover the insurance, pay for the phones, and a whole pile of other expenses can be deducted at tax time. And in time when we move in to the main building we will not only eliminate 100% of my wife's commute, we will also be living there largely for free.
But even if moving was not in the cards we could carry both mortgages indefinitely. Having a renter, especially a long term built in one, makes the decision a lot easier.