This set contains four versions of the same collector $1 coin, each with a different mint mark or privy mark - C, B, M or S respectively for Canberra (mint mark) and privy marks for Brisbane, Melbourne and Sydney.
The RAM says about the set:
"The Australian gold rushes led to the development of modern Australia, but life on the goldfields could be harsh. The remote desert landscapes of Western Australia needed supplies, and camels were ideal for the job. Camels were imported into Australia by ‘Afghan’ cameleers, and were crucial to WA’s gold industry. We honour the hardy camels and their enterprising cameleers with this 2020 mintmark and privy mark four coin set."