There are many fakes of WA Pfretzschner in the market, including one discussed here at maestronet awhile ago: http://www.maestronet.com/forum/index.php?/topic/327915-is-this-wa-prefetzschner-violin-bow-i-just-bought-fake/?hl=pfretzschner
How about this one? Is this a workshop bow?
As far as I know, there were many different bow makers working in his Markneukerchen shop during 1894-1947, all stamped with the shop brand.