Actually, there is, I believe, only the single M1909 holster, but made by two different makers in different periods, so their markings are different. Both holsters were intended to carry the same Colt New Service revolver (and also the S&W M1917 revolver during WWI). The Colt Model 1909 and the Colt Model 1917 revolvers are variations of the Colt New Service (but in different calibers) and are dimensionally identical. Far fewer Colt M1909 revolvers (and holsters) were made than M1917s, less than 20,000, and M1909 revolvers are seldom found today. The original M1909 holsters were made by Rock Island Arsenal in 1910-11, and are so stamped, while the WWI-era holsters were made by a contractor, G&K. Those are marked G&K 1917 and 1918, and are fairly common, albeit not in great condition. The original Rock Island Arsenal made and marked M1909 holsters are very scarce and valuable, as most of them never made it back from the Philippines. I have read that some holsters for the M1909 revolver were also made at the Manila Arsenal by modifying earlier military holsters (except for a very few issued stateside, almost all Colt M1909 revolvers were shipped to the Philippines for use against the Moros, many never to return). I have two M1909 Colts, and have personally seen only two others, both of which were in much lower condition than mine.
There are probably others more conversant with military holster lore of that period who may be able to add better information.
