Does an abdominal ct scan with and without contrast have the same amount of radiation as two ct scans?

Yes: However, there are techniques to reduce radiation exposure. Also, make sure you ask the reason for both scans, as many times there is no clinical need for both. I there is a sound reason however, then proceed as your doctor advises.

Yes: The ct scan will consist of at least 3 parts. A very low dose scan to show the anatomy and allow for planning of the full ct scan. The next scan is the "real" scan without contrast. Then there will be at least 1 scan with contrast, usually when the veins are most opacified, at about 70 seconds after the start of the injection. However, some contrast scans have multiple phases for some anatomy.