According to the book "Das Tankgewehr Mauser M 1918" by Wolfgang Kern (ISBN 3-933481-06-6), the bipod in Jim's 1st foto is an original Tankgewehr bipod, made from solid material - and very heavy. There are probably very few of those still around.
The one favored by the PBI who had to carry all that gear was the bipod for the MG 08/15, which was a much lighter "plug-in" replacement. That is what Randy has got. There are probably considerably more of these around, reflecting the larger quantity of MG 08/15s.
The book also mentions (P116) that if one had to make a "strategic withdrawal" the heavy bipod was the first thing to be dumped, and also observes that the majority of photos of a T-Gewehr in action show it without a bipod at all. Many riflemen would have seen little sense in using a bipod (which anyway tended to sink into the muddy earth) and thus be forced to stick one's head out further than absolutely necessary. Resting the beast on the parapet of the trench was simpler - and safer!
Randy, that book is a must! And if anyone knows a better one on the T-Gewehr, please let me know!