So!
Let us lay out the scenario of Messrs Nickerson and Mytton...
Scene One: Wednesday, 25 March 1964, 9:45 am-Agent Howlett visits the crime lab and tells Lieutenant Day he needs these two curtain rods tested for Mr Oswald's prints because the investigation still lacks ironclad proof that Mr Oswald was ever in the Paine home
-Lieutenant Day, not being a moron, gives Agent Howlett an incredulous stare but, being a professional, takes the package and reaches for an official sign-in/sign-out form
-Lieutenant Day, being a moron and not nearly as punctilious when it comes to trivial things like dates as a Person Who Signs For Commercial Deliveries, enters the date as 15 March instead of 25 March
-Not being a moron, he gets everything else right: "2 curtain rods, white enameled (4 pieces) marked 275 & 276"
-He signs his name in the appropriate field and gives the form to Agent Howlett for his signature
-Agent Howlett, being a moron and not nearly as punctilious when it comes to trivial things like dates as a Person Who Signs For Commercial Deliveries, doesn't notice the wrong date and happily countersigns
Scene Two: Wednesday, 25 March 1964, time unknown-Lieutenant Day, not being a moron, engages in the specialised task of testing the curtain rods for fingerprints and cross-checking these against Mr Oswald's prints
-Lieutenant Day, not being a moron and being as punctilious when it comes to important things like dates as a Person Who Signs For Commercial Deliveries, correctly notes the date on the first card: 25 March
Scene Three: Thursday 26 March 1964, 7.50 am-Agent Howlett comes back to pick up the curtain rods: he is distraught to learn from Lieutenant Day that, as Mr Oswald's prints are not on them, the investigation still lacks ironclad proof that Mr Oswald was ever in the Paine home
-Lieutenant Day pulls out the sign-in/sign-out form
-Lieutenant Day, being a moron and not nearly as punctilious when it comes to trivial things like dates as a Person Who Signs For Commercial Deliveries, again fails to notice the wildly incorrect date at the top of the form
-Lieutenant Day, being a
complete moron and not remotely as punctilious when it comes to trivial things like dates as a Person Who Signs For Commercial Deliveries, compounds his earlier mistake by now writing today's date (26 March) as 24 March
-Agent Howlett, being a complete moron and not remotely as punctilious when it comes to trivial things like dates as a Person Who Signs For Commercial Deliveries, fails to notice that the official form he is being asked to sign for a second time now contains not one but two incorrect dates, and so he happily countersigns
Scene Three: Thursday 26 March 1964, time unknown-Lieutenant Day, not being a moron and being as punctilious when it comes to important things like dates as a Person Who Signs For Commercial Deliveries, notices in glancing over the form that the date of release is two days out... 'How could I have been such a moron and not nearly as punctilious when it comes to important things like dates as a Person Who Signs For Commercial Deliveries?' he says to himself, and determines to haul out an earlier copy of the incomplete version of the form so he can fix the moronic error
-Lieutenant Day, not being a moron and being as punctilious when it comes to important things like dates as a Person Who Signs For Commercial Deliveries, gets the date of release right this time: 26 March
-Lieutenant Day, not being a moron and being as punctilious when it comes to important things like timestamps as a Person Who Signs For Commercial Deliveries, knows to consult the original completed form before entering the time at which the rods were released: 7.50 am
-Lieutenant Day, having gone to all this trouble to fix a moronic date error but being a moron and not nearly as punctilious when it comes to trivial things like dates as a Person Who Signs For Commercial Deliveries,
still fails to notice that the date of submission is wildly out, so he leaves that date stand: 15 March.
Solved!