you can usually get a pretty good idea depending on patterns ( similar to sikorae and henkeli patterns)
some uroplatus will have a slight bulge, but two adults of the opposite sex are very easy to dinstinguish.
both sexes should be just about equally imported, however the % of females that become available to the public after importation, # of females that die during importation or shortly there after due to being gravid/unhealthy, and the # of first come customers may make it seem like there are more males available.