Tanzania, Espana And Nepal Overprints? Or Odd Cancellations

Hi all. More oddities to enjoy from the inherited collection. Hope you all like.

The Last 6 are Charity Labels (Spain)
No Postal Value.
For the Orphans of Postal workers, I believe.

Tanzania: OFFICIAL overprints are listed separately in Scott and were used by governmental offices. This overprinting was done by many countries even back to the earliest stamp issues, including overprinting with OS ("On Service") or the initials of governmental agencies. It saved on creating new designs and printing them, though some countries did do and still do that for official stamps.

This was done as a control to keep people from stealing postage and using it for personal mail.

Nepal: Their official overprint.

From my collections.