I don't think anything was altered but Day signed the original and at a different time signed Howlett's incomplete copy, which became the WC exhibit.
JohnM
So if I understand your idea, the original, was copied, but at a time it was incomplete, some time before the 24th. It simply had the submittion information (the stuff in red) and Howlett's initial signature. The original was then completed properly on the day they were handed back, with the 24th added, time and Howlett?s second signature along with Day's.
Then Day, when asked to provide the documentation concerning the Paine rods, could not find the original, and decided to add what he could. His signature, the correct time, and a date that he guessed incorrectly, the 26th. This was submitted as the WC exhibit.
Later the original was found.