Hi S. Coe,
At this time, the only options for recurring payments are Monthly and Yearly. Unless I'm misunderstanding what you're trying to do, they wouldn't need to purchase 2 1-year subscriptions; it will renew every year, so they'd basically be paying twice for the same product.
PayPal does automatically bill them each month/year, however you have it set up. It does not send a reminder email, though, when it's time to renew, just when the initial payment is made.
Let us know if you have any additional questions.