Also, being the owner of a fine 1914-production pistol, with its original lanyard-loop magazine, I have often pondered the same questions as John. After seeing this topic, I did a bit of Googling which hasn't yielded a lot of information ... but in one discussion on the militaryhorse.org forum back in 2012 it was noted that early regulations stated:
When a lanyard is used, the snaps are attached to the butt of the pistol and the magazine; the sliding loop is passed over the head and drawn snug against the right armpit. The lanyard should then be of just such length that the arm can be extended without constraint.
(The exact same wording apparently appeared in both the "Cavalry Drill Regulations, 1916, Manual of the Pistol" and as a change to the wording of the "Signal Corps Drill Regulations" effective 16 August 1915.)
The consensus in that discussion (to the extent there was one) was that there was apparently a M1912 lanyard (although few, if any, examples are known to exist) which had two separate hooks, one of which was attached to the loop on the pistol and the other to the loop on the magazine, in accordance with the passage quoted above. The magazine lanyard loop on the magazine was apparently eliminated fairly early and the M'1917 lanyard, with only one clip, was adopted. One chap posted a photo purporting to show the two types of lanyard (although the double clip one at top is missing its sliding metal clip which held the two cords together, and they also weren't sure if it was an actual M'1912 lanyard or something else) -
These are lanyards for enlisted men, by the way ... rather than worsted cord, Officer's lanyards were made of leather, which is apparently what is depicted in this representation of an Army officer at the time of the Punitive Expedition. It does, however, more or less show the loop "drawn snug against the right armpit", as specified in the Drill Regulations -
If I had to hazard a guess, it would be that the magazine in the pistol when holstered may have had a second lanyard clip attached, but that it would be unlikely that spare magazines carried in the belt pouch would also have lanyards attached to them ...
If there
was a consensus in the mentioned forum discussion, it was that period photos or other illustrations showing ANY 1911 pistol lanyard in actual use by US troops are rare ...