Don't mean to hijack this thread but I was intrigued by the post and thought I'd post a picture of mine. I have a double stamped DWM that I posted about some years ago that had police modifications done and then removed. I'm afraid I don't know how to post a direct link to my original post but it was titled "Please Help Identify Unit Marking on 1916 DWM" and was posted on 4/19/2011.
Here is a pic of the back strap on that pistol.
Here is a pic of the front stamp marking