Imprint of reverse on obverse of coin

I'm wondering what's going on with this Indian coin, and whether this imprint qualifies as an error. I've never seen anything like this before. The outline of the reverse of the coin seems to be imprinted in the obverse. The coin is KM #154, 5 Rupees, 2002 ♦: https://en.numista.com/catalogue/pieces1608.html





EDIT: I have just noticed the same thing has happened on the obverse, although it's much fainter!

It is called a brockage.

In this case, Zac, I would rather say it's a die clash. At some point the two dies clashed and damaged each other because there was no planchet to be struck in-between. When this happens, the lower parts of the die are left untouched and that's why the most prominent parts of the design on the coin are not affected (unlike brockage).

What's interesting is that we rarely see both sides affected. It seems that usually one of the two dies needs to be replaced, as is the case with my recently acquired Napoleon 5 francs. So, it's an interesting piece though you're not going to be able to retire early with the small premium you'll get if you sell it...