Originally Posted by stl09 
Mark,
Thank you, that answers the question and that's what I thought and couldn't really figure out why someone would need both.
The 50mm would be of more use for someone photographing inanimate objects - stamps, jewelry, etc. The depth of field is roughly double at the same magnification and aperture, and the perspective is different as well.
The 100mm is a better choice for taking pictures of creepy crawly things that fly away when you get too close.
The FA* 200mm f/4 Macro would be even better, but my wife won't let me mortgage the house to buy one.