What Casper is showing you is the old style Banjo which would be legal in Queensland.
I believe you are asking about small highbankers. The two tiered version of a highbanker is known to some as the modern Banjo.
http://www.gold-net.com.au/archivemagazines/may02/59329034.html#3
Under the letter of the law they aren't legal in Qld. Their Fossicking Rules & Responsibilities states "Hand tools such as picks, shovels, hammers, sieves, shakers, electronic detectors and other similar tools can be used.No machinery is permitted." This isn't specific to any particular activity such as excavation & is more of a blanket statement than other states so creates the no machinery at all thinking.
You could argue the intent of the legislation, which I believe in reading it & other states, isn't for small devices such as a modern banjo/highbanker & was more aimed at ensuring large machinery isn't used in excavations or processing. Unfortunately it's poorly written, non specific & open to how enforcers + prospectors/fossickers can interpret it.
My way of thinking is when in Rome do what the Romans do. If people are highbanking without issue have a crack to - if they aren't or there's signage with things like no pumps, no generators etc. then give it a miss in those areas.
p.s my way of thinking may not hold up in a court of law :lol:
If I lived in Qld I would be pursuing avenues to have the intent more closely looked at & ways to get the current wording relaxed + being more specific to allow small apparatus such as highbankers allowable. In saying that I have seen examples in other states of people pushing the boundaries by building monster highbankers etc. to expose legislation in their favour. My opinion is this can be just as damaging & unfair to the average prospector as refusing their use at all. It's a two way street.