Stamps on stamps is a philatelic term for depicting images of postage stamps on postage stamps. Some postage stamp collectors have specialized in collecting stamps on stamps as a topical collection.
Type A – Stamp that contain (fully or partly) the original stamp (some times with modification). Type SY / U - Stamp that contain an unidentifiable form of stamp: stamp on an envelope, symbol of stamp, etc. Type B – Stamp that contain something of the original design or that use the same design with modifications.
Pakistan
Pakistan have issued three stamp on stamps from 1947 to 2014