one time i have seen double-hets from two different ghost lines for sale, a breeder obviously tried out the compatibility and the lines were incompatible.

if you are lucky, you might find some for sale somewhere. and you might find breeders that have two different lines in their collection that are proven out to be incompatible.

interesting project, so far i have not heared of anyone doing a double-recessive double ghost. what has been done and is being done is the axanthic ghost = "true ghost". so, yes, interesting.