I agree on this. I have not seen this with most of my dragons but did have one female that definitely laid eggs long after the normal 3-5 month gestation. I believe that sperm retention is possible.

There have also been several documented cases of females laying infertile eggs under optimal care or when aquired as new imports. My take is to always treat them as fertile until they are obviously not!
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Marcia - FroggieB Dragons
www.froggieb.com/MHDHome.html