DH x DH involving DH's for 2 different strains of Axanthic (i.e DH VPI / TSK Axanthics bred together). I know there are some DH Axanthics out there, as some people, especially Mike Jolliff, have tried to breed 2 strains of Axanthics together to prove compatibility. So, DH's definitely exist. I just have never seen any documantation of them being bred together and what the outcomes were.
I have long thought about getting another line of Axanthics just to try the breeding.