Replica

Replica: A reproduction of a stamp or cover. In the 19th century, replica stamps were sold as stamp album space fillers. Replica stamps are often printed in one color in a sheet containing a number of different designs.

Replica: A reproduction of philatelic material.
Retouch: The repair of a damaged plate or die.
Rust: A brown mold on stamps.

Replica Penfold in Singapore for collecting special Christmas Post
A PB8/1 Penfold at Prince Edward Rd; one of six in Cheltenham
Original bronze-green livery Penfold on High St Rochester, Kent showing enamel Letters flap ...

A replica of a genuine coin created by making molds of the obverse and reverse, then casting base metal in the molds. A seam is usually visible on the edge unless it has been ground down.
Castaing machine ...

Replicas: printed stamp reproductions were made as space fillers; usually printed in one color, mostly blue, for collectors to use to fill blank spaces in their albums.

Counterfeit - an item, usually a replica of an existing stamp, made to defraud collectors. The term can also be applied to overprints, postmarks, etc.

They are replicated together with other stamps accidentally. The most famous error stamp is the Inverted Jenny stamp.

While fakes, forgeries and counterfeits replicate the design of real stamps, bogus stamps, also called false emissions, pretend to be real postage stamps without replicating the design of genuinely issued stamps.

What you have are not actual postage stamps but stamp replicas. Because few stamp collectors are interested in these and there is not much of a resale market, dealers are unlikely to pay much for such collections.

These are usually called "Postage Currency", because the images in the centers are basically the then-current stamps of 5c and 10c denominations, singly or replicated - you may not be able to see it on these scans (I swiped them all from ebay ...

See also: Stamp, Used, Sheet, Local, Printing