Interesting story about Newspaper stamp facsimiles, as told by Doc Pepper in his four volume study.
From the time that they were initially released, the 1875-1885 Newspaper Stamps were quite expensive and difficult to obtain. Federal regulations did not allow the sale of newspaper stamps to the general public, and even if they did, the total face value for a complete set was over $200, a lot of money in 1875.
A German stamp dealer (the Senf Brothers) created some high quality engraved facsimiles of the early newspaper stamps, not to defraud collectors, but to let them fill their albums with high quality reprints. It was clear in their ads that they were selling facsimiles. "... a large number of blank spaces are found in almost all collections on the pages prepared for these stamps. This causes much unhappiness among collectors as they leaf through their albums. ... Every collector now has the opportunity to acquire facsimiles of these miniature works of art for a relatively small sum."

The first printing (type FA) has the word "FALSCH" carefully worked into the stamp design. Doc Pepper writes that the Senf Brothers did not intend for these imitations to get confused with genuine stamps, but the quality was so good that there was ample opportunity for general collectors to get deceived. So in the second printing (type FB), the stamps were overprinted "Facsimile". This was not enough, because the overprint was just 1 mm tall, so a 3rd printing (type FC) increased the size of the overprint by 50% to 1.5 mm and upper case "FACSIMILE".
Doc Pepper continues, "Being respected dealers with a line of albums, regular catalogs, and other philatelic material, the Senfs were sensitive to the growing criticism of how the facsimiles fooled collectors. This probably accounted for the Senf's steady re-work of the overprint." The 2 mm tall overprint of Type FE may be yet another attempt to stave off criticism, and then the 2 1/2 mm overprint (Type FF) appear to be the Senf brother's "final solution".
The following picture shows a progression of the overprint in increasing size. Items from
ebay.

"Despite the fact that large FACSIMILE letters made it very hard to mistake the FFs from the originals, criticism of facsimiles in general by the stamp collecting public continued to grow and a poll of Senf subscribers in 1890 revealed over half felt the practice should be discontinued," which they did, and which is why Senf did not produce the 1895 newspaper stamps as facsimiles.
fyi, Doc Pepper's books can be found on
ebay. I have no relationship to the author or to the vendor, just a satisfied customer.
https://www.ebay.com/itm/306176046516