Yep, in ball pythons the term "True Ghost" has been used for the expected double homozygous hypomelanistic (AKA "ghost" in ball python speak) and Axanthic. I don't think anyone has produced this yet but hopefully this year someone will. The reason for the "true" part is that in most other species "ghost" is used for the combo of hypomelanistic and axanthic/anerythristic but in ball pythons it got applied to a single mutation. Some have tried to get the industry to start calling ghost balls - hypomelanistic to avoid this confusion but the term "ghost" seems to stick.
Once we are a little further down the true ghost project there will be many ways to produce them - for example true ghost X true ghost will produce 100% true ghosts and true ghost X axanthic, het ghost will produce eggs 50% chance true ghosts. However, the first true ghost will probably be from the 6.25% (1:16) chance from each egg from crossing a pair of double hets created a couple years back by crossing hypomelanistic and axanthic.