
Some crossbreeds are very predictable in appearance - go to a lurcher show and look at the bedlington x whippet classes!
Some are less so - first x labrador/standard poodle has a much greater variety of appearance, size. shape, coat type..
Lurchers are bred to do a job so its not uncommon for different people to breed the same crosses if they want to do the same job in the same sorts of conditions, and of course people choose those particular crosses based on their own and other peoples experience with that cross, rather than go for an unknown untried mix.
Greyhound/deerhound/wheaten is not a hugely uncommon cross (less common these days but trends change and go round again) and a pretty predictable one, I wouldnt at all be surprised to find two totally unrelated dogs of that breeding that look identical.