I took some time out of all the very important things that I have to do (in other words, sit around, sit around some more, and then sit around further) and took a typing test to see how fast I could type, the first time with both hands, as you do, and then the next time with just one hand. Here were my results:
Both hands: 106 WPM
Right Hand: 30 WPM
Left Hand: 26 WPM
I wasn't surprised that I could type a little faster with my right hand than with my left, since when I usually have to type one handed, it's with my right.
How about you? http://www.typingtest.com/