The color on the doors should be matching to allow for a pleasing color scheme. Usually doors contrast in color by complementing the house's paint. I prefer light pastels like tan and green doors.

I personally would paint them the same color. If you painted them different colors it most likely would offset any color scheme you have going with your house. What I mean is if you took a complete walk around the house it would be very noticeable to anyone paying attention. I believe you should keep in line with your current color scheme you are using for window trim or other trimmings and paint them the same color. I wish you much luck in whatever you decide to do!