A little research confirms that image of Varahi you've posted is concerned with or related to the Drikung Phowa practice, which was commented on here in this thread. I understand they have a unique Phowa transmission. The fact that the Thangka contains a single figure, with no other deities, leads me to think this--as does the seated Amitabha image...
Here is the full lineage thangka for the Phowa Jag-tshug-ma (a.k.a. Great Drikung Phowa)---the same image given to those who receive the empowerment. The practice originated as a Nyingma terma and was eventually given to the 1st Drikung Kyabgön Chetsang Rinpoche, and hence became a specialty of the Drikung Kagyupas:http://www.garchen.net/resources/phowa-lineage-tree5x7.jpg
A detailed history of the practice, just as it is included at the beginning of the elaborate sadhana, can be found here:http://www.ddcflorida.com/2009/01/jag-tshug-ma-standing-blade-of-grass.html
As for the difference between the Kamtsang and Drikung versions of Vajravarahi, quite honestly I didn't even notice that the leg raised differs between the two lineages at times, despite these being the two Kagyu lineages I have the most experience with. Is there significance in which leg is up, or are we simply used to it being the right leg? Could the placement of the sow's head be artistic license?
That said, I do know that 'Vajrayogini with the Faces of the Two Truths' is the Drikung Kagyu practice, whereas I may have dealt with mainly the Yangzab version of Varahi due to involvement in Lho Ontul Rinpoche's Drikung Dzogchen Communities...
Whatever the case, lasirene, rest assured that the essence of all deities is the same. Vajrayogini manifests in a multitude of forms to benefit beings with varying capacities and propensities, and Vajravarahi is an especially important yidam (if not the main
one) for all Dagpo Kagyu (the 4 elder and 8 younger lineages).
Perhaps someone with more experience with the Shangpa Kagyu can comment on how central she is there?
"The Sutras, Tantras, and Philosophical Scriptures are great in number. However life is short, and intelligence is limited, so it's hard to cover them completely. You may know a lot, but if you don't put it into practice, it's like dying of thirst on the shore of a great lake. Likewise, it happens that a common corpse is found in the bed of a great scholar." ~ Karma Chagme དྲིན་ཆེན་རྗེ་བཙུན་བླ་མ་རཱ་ག་ཨ་སྱ་མཁྱེན་ནོ།