I haven't been able to find any further memorandum on this issue.
I'm not sure what dailies Justman was watching (I found the memo in a box and folder devoted to wardrobe items, not a particular episode).
The information I have indicates that "The Omega Glory" was filmed on December 18-26, 1967. I was under the impression that it took 24 hours to turn around dailies, but perhaps a date is slightly wrong somewhere, and that's the episode Justman was watching dailies from.
Justman couldn't have been watching dailies from "The Doomsday Machine," though. That was filmed on June 20-26, and broadcast on October 20, 1967, months before Justman's insignia memo.
According to "Inside Star Trek: The Real Story," Bob Justman came down with a very serious infection in his hip just before the start of the second production year. This caused him to be hospitalized and miss working on some of the episodes produced early that season. So I wondered if he could have missed the production of TDM in late June of '67... but accoding to the book, he was back at work well before then. So just how did he fail to notice Decker's insignia in the dailies then?