This weekend I had an experience I hope does not repeat itself. At 3500 feet, I pulled my pud and tossed my pilot out. I expected the usual tug from my main canopy opening but it didn't happen. At 2200 feet I pulled my reserve and left my main cutaway handle in place. The reserve opened fine, but I immediately felt a second tug and discovered that my main opened. The reserve went into a down plane facing me and my main went to my back in a downplane. At first it created a rocking motion but quickly turned into an accelerating spin. I really don't know caused this to happen. I think either my main's pilot was not catching air and was in my burble or I had some sort of bag-lock that popped free when my reserve deployed. What do you think? What would you have done differently? Oh and yes, I landed off but safely. Thank God for baseball fields!