On the page it is mentioned that this problem is part of the Xuan Xuan Qi Jing, but it is not among the problems listed at Xuan Xuan Qi Jing Problems. There are, however, different versions of the XXQJ. As John Fairbairn discusses in the fourth paragraph of his introduction to the XXQJ: Some have 376 problems, some have 378, while others reduce the figure substantially because of duplications.
Senseis currently has 347 XXQJ problems, should we perhaps add this as problem 348? Making Xuan Xuan Qi Jing Problem 348? an alias to this page?
There is already a link from Xuanxuan Qijing Problems to 1-2 point problem 1?, except that no number is assigned to it.
Ah, I see it now. I found this page via Dan Exercises, and when I saw the XXQJ reference, I went looking through all the XXQJ thumbnails to see if it was a duplicate :)