Stamp on Stamp

I have been fascinated by the Stamp on Stamp theme. Not as much about collecting those stamps that have stamps represented on them, but collecting the pairs with original stamps and the stamps commemorating them. Kinda sounds confusing, all these stamps on stamps words. Here's what I am talking about.

Technically the stamp on the left isn't 1852 Britannia stamp that's being commemorated in the stamp on the right. Its actually either 1860 or 1871 rough perforation one. But hey, for the purpose of collecting stamp-on-stamp theme, I think I'll sneak this through 😉

In this one too, the classic India Four Anna is not the same as that shown in the Philately Day stamp on the right. What the right stamp (minisheet) has is an error variety of the classic Four Anna stamp. I guess this will do for my collection, given the rarity of the error variety.