The square blade of the shovel is more effective for digging a vehicle out of snow, than for digging in soil. Back in the day, we carried such shovels when skiing at Buller or Hotham.
The two that LE have retrieved may not have anything to do with this case. It's a bit unfathomable that any murderer would dispose of shovels by casually leaving them in the bush, rather than at least burying them.
If those shovels are connected with the disappearance of Carol and Russell, perhaps they were ditched in a moment of panic, for example, if the white ute was indeed the getaway vehicle, when public appeals for information about it were made, IMO, the occupant/s of it would have been seriously alarmed.
It still appears to be very careless disposal of potential evidence, especially if it was done by the same person/s who killed Russell and Carol, and took the time and effort to burn their campsite in an effort to conceal evidence.
Something that puzzles me particularly is the appearance that someone rifled through Russell's vehicle, and left cards from his wallet strewn on the seat, then locked the door of it.
When was this done? It's difficult to imagine it taking place whilst Russell and Carol were alive or conscious, unless they were restrained in some way.
Or were they asleep in their tent, woke up, and challenged the vehicle's intruder/s, which ended in their murders?
It's likewise difficult to imagine after killing two people, heaving their bodies to anywhere at all, a perp. would dally at the murder scene to search a victim's vehicle for what? Credit cards, whose usage can be traced?