I am certain the nip slips are real. Look at the filenames, the alphanumeric portions start with 00084, 00168, and 00185. Now go back and look at the Mega posted in the thread on March 13. The images with five digit numbers as filenames are what we are interested in. They are numbered 00001 through 00201, with four numbers missing: 00167, 00168, 00176, and 00185. Two of these are our images in question, and the other two are unaccounted for. The third image in question, 00084.jpg, is there nipple and all. I don't know how I missed it in there when I originally downloaded the folder.
The content of the images also makes sense chronologically with where they fit in the numbering. So these images must have existed when the folder was created, and were pulled out presumably for showing too much. How they reemerged is still a mystery, and hopefully 00167 and 00176 will make an appearance at some point.
The chances of someone managing to make such perfect edits, starting with images none of us have seen before, and fitting them into preexisting file naming are astronomical. I just don't think it is possible, and the images must be authentic.