If there are 3 two-hour naps during each day, that means 6 hours is taken up with naps. Try looking at your problem backwards: 6 hours naps means 6 hours awake time (sort of). Which 6 hours are both of your kids awake?
If it happens to only be during meal times, try this: while one is napping, pack a picnic lunch and head to the park if they're both awake during lunch. (You can do the same for dinner, and include your spouse as well.) If they are both awake at breakfast time, nurse or bottle feed the baby, and let the two year old eat a breakfast bar in the car on your way to run a few errands.
I never let my son's naps interfere with my schedule. If he is napping while I am running errands, he sleeps in the cart. If he is napping in the car, fine. It would be harder with two, but still doable, especially if your baby can rife in a sling, or front pack carrier, or stroller. A double stroller might be the ticket for you. Either can sleep, and you can get in a good walk, either outside or at a mall, etc.
Also, whenever one or both are sleeping, that might be a fine time to ask a neighbor, friend, or relative to come over and watch them while you take a walk outside or drive to the local coffee shop or whatever for a break.
Let us know what you end up doing. My sister is a slave to her son's naptime, because she never taught him - or allowed him- to sleep anywhere else. I just couldn't handle life like that, so my son adapted to my routines, and we both are happy with the results.