'Billig's grosses Handbuch der Faelschungen' describes two different forgeries of the Schipka Pass series. The story tells that the Type I forgeries were made in large quantities at the end of 1902 by a group lead by an artillery officer named Bukowsky, who got the necessary equipment from the artillery laboratory in Sofia. The forgeries were sold through regular stamp retailers, and caused great losses for the Bulgarian post.

Type II forgeries were made a few years later in Constantinople, and have poorer quality. In contrast to Type I these forgeries were made for sale to gullible collectors.

At first sight, forgeries of the series Mi 62-64 looks very real. Comparing with original stamps, however, several errors and inaccuracies are revealed in the design details. According to Billig's Handbuch the forgeries can be separated from the original issues by the following characteristics (valid for all three issues):
 

Original	Type I forgery	Type II forgery
The cyrillic 'P' in the word 'SCHIPKA' is closed by a thin horizontal top line	Top line of 'P' missing	'P' has thick top line
Angular 'A' with horizontal top and three distinctive parts in 'SCHIPKA'	Rounded 'A'	Top often missing, mid part connected to top and bottom
Detached horizontal line ends over 'I' after 'SCHIPKA'	Line connceted to frame	Point on line connected to frame and letter
The number '2' in '1902' detached from ornament	'2' connceted to ornament	'2 connceted to ornament
Detached horizontal line over last letter in right text field	Line askew towards frame	Line connected to frame
Thin braided bands, horizontal shading	Broad bands	Broad bands
The gun is close to the bayonet, 3 lines of muzzle flame shown. 4 fingers drawn on the fallen's left hand.	The gun is farther from the bayonet, and the 3 lines of the muzzle flame are insufficiently drawn. Only three fingers on the fallen's left hand.	The gun is too close to the bayonet
Angular 'A's in left text	Rounded 'A's in left text	Non-detached mid part of 'A's

Please note that a change of scanner has made the pictures of the original stamps look more blurred than they actually are.

Forgery	Original

Sources:
- Billig's grosses Handbuch der Faelschungen, Part 34, Vienna, 1937
- F. Serrane: The Serrane Guide, APS 1998