The knot structure looks familiar to me, but I can't be sure if i stumbled upon it in my knot wanderings of yore.
Pulling on the tails brings the twin nipping turns together and this would appear to make the knot difficult to untie. However, keep them somewhat apart, as in your last frame, and it should always be easy to untie. Too much apart though and the knot can morph into a very different sennit-like form.
Regarding a name, I have no clue.