I saw what is sometimes referred to has a "two-date" or "true" double date at a gun show this weekend. It was an Erfurt 1917/18 in decent condition.
Here is a link to a discussion on them in a 2004 thread on the JCS forum.
http://luger.gunboards.com/showthrea...ue+double+date
At that time only a few had been reported. Any new thoughts on them? Do these have any more value than a regular 1917 or 1918 Erfurt? I know sometimes rarity does not equate to increased value.