Today I have been working on P64. Take a look at the image of one of the fragment (frg. c) of P64.
In C. H. Roberts editio princeps he transcribes the second line (col. 2, verso frg. “c”) ι]β [ο] λεγομ[ενος (Matt 26:14) which is obviously erroneous.
K. S. Min points out, in his study of the Matthean papyri, that there is no space for the omicron and so transcribes ι]β λεγομ[ενος (followed by Comfort and Barrett).
The omission of the article would be a unique reading. However, the rounded bottom of the letter is a bit different from how the scribe wrote the letter beta elsewhere (twice in 67). Further, the trace of the extant letter before λεγο[μενος could perhaps also be an omicron written in smaller size. The letter is admittedly written somewhat below the line, which speaks in favor of a beta.
On the other hand, there seems to be at least one other example of a smaller omicron in this manuscript, see this image of line 2, col. 1, recto of this fragment:
What is your opinion?
Update: I have uploaded a better image of P64 (col. 2, verso frg. “c”)