Maybe I am heading for another record low number of views with this post, but I would be interested to know how the mirrored writing came about. Wikipedia has an article on GA 101, but does not mention the phenomenon, nor does any other source I have. I am not an insider at INTF, so I don't know what other information may be available. Perhaps someone could add the story in Wikipedia? Or is this news to our generation (though others must have seen it)? Attached are two screenshots of the more legible part of the page I was studying. My transcription from the scans involves some interpolation.
1. from image 950 column 2 starting at line 15, showing 1 Timothy 3:11. μὴ διαβόλους νηφα λέους πιστὰς ἐν πᾶσι διάκονοι ἔστωσαν μιᾶς
2. from image 960 column 1 mirrored, starting at line 15, showing 1 Timothy 5:17. κοπιῶντες ἐν λόγῳ καὶ διδασκαλίᾳ λέγει γὰρ ἡ γραφή βοῦν ἀλοῶντα
You can see that the page outlines match, as we have recto and reflected verso of the same page. There is perhaps even a third layer of writing, because where do the large Μ and Ο on the first image come from? As can be seen, they are not from the verso.