There are numerous proofs in existence printed on card rather than India paper.
It is difficult to see how these items could have been part of the actual process of
developing the design of the stamps since India paper was the preferred choice for high quality
impressions. Most likely they were souvenirs, printed well after the stamps had been designed.
This is certainly true of the Revenue War Tax and Excise Tax items,
which were mounted together on a large card showing values from 1c to $100.