As an old school typist, I always used the lower case “l” for a one. It was acceptable. It does appears to be two separate typewriters. As for no letterhead or signature, we always put the carbon copy in the file (no photocopiers). The carbon paper had no letterhead and most people did not sign the letter with the carbon paper still in it so a signature would be in the file. As for the analysis of the font type, etc. I will leave that to the experts.
On a memo to the file such as by WlMix, there would generally be no carbons and the original would go in the file as it was just a work file, used to record information that had been gathered, facts etc, in case the file was turned over to another office or officer, due to transfer, leave, etc. That new assigned officer or office could pick up where the old one left off. That is one reason I find it strange that the source of the information stating Obie was born in Hawaii is missing..someone else picking up the file would not know how it was checked and would have to start over.
The second reason I doubt anything more than a telephone call to Hawaii vital records for a cursory index search or a call to Stanley Ann was made is due to the nature of the “inquiry”,they used the word inquiry not investigation when referring to the directive to get the info. Thus no emphasis or suspicion seemed to be in order, but the fact if he was a USC and whether her previous husbands child or Lolo’s child was the main point of the inquiry, and likely a point a supervisor found on a checklist of things that should be done. It appears on document 43 page that WLM hand initialed that doc or had a very brief and unusual signature. that doc was dated sept 25, 1967. Doc #45 is blurred and appears to be a carbon copy while doc #46 is clear and no smudges, to me indicative of an original not carbon.