The xNT is not a DESfire tag. They are not compatible. The xNT cannot be cloned to another card.
The FlexDF is an 8k DESfire tag
But it cannot be cloned either. It is a secure card. But you may be able to get your company to enroll the tag in their system. See the FlexDF section on this page:
We often get asked which of our products would be the best one to use with access control system X or product Y. The answer can be a little complicated. We do have a running list of products that we need your help keeping up to date, but there are so many systems out there, I figured this write-up would be the best way to go about explaining things.
Basically, using our products with some system or reader comes down to two major things… chip compatibility and magnetic coupling.