No, there are two doors, not two sets of doors. And no front part. Mr Oswald was describing the front entrance on the first floor.
It appears Mr Oswald did use that word. Its primary meaning is front lobby, but it can also mean portico or front porch.
Mr Belin, during Mr Roy Truly's testimony, makes sure to misdescribe the space you refer to as a 'vestibule'.
~Grin~ Your gift for tuning out uncongenial data is impressive, Mr Nessan!
Mr HOLMES. ... But he went downstairs, and as he went out the front, it seems as though he did have a coke with him, or he stopped at the coke machine, or somebody else was trying to get a coke, but there was a coke involved. He mentioned something about a coke .
Mr Holmes is certain about the front entrance to first floor part, a lot less so about the coke part ("Seems like he said... It seems as though...")
Mr Oswald did indeed mention something about a Coke--a Coke which he had bought from the machine up in the lunchroom before the motorcade and which he now had in his hand at the front entrance when the officer came storming up those steps.
He radically changed his story in this final interview. He abandoned the idea he ate lunch with or near the coworkers. He admitted to being on the upper floors during the assassination based on his continuing to work until he came downstairs because of th commotion and encountered Baker in the 2nd floor lunchroom. I agree It is hard to believe he would do this but maybe the confusion of the interview played a part. In the end I really don't think LHO was that clever or an actual plan existed to assassinate JFK and for him to escape. It reinforces the idea it was totally spur of the moment
Mr. HOLMES. There was no formality, to the interrogation. One man would question Oswald. Another would interrupt with a different trend of thought, or something in connection, and it was sort of an informal questioning or interrogation. The confusion of having a number of officials and the randomness of the questions may have placed LHO off guard. All that is reported is the answers never the questions or statements by the officials. It is entirely possible someone told him his coworkers denied seeing him at lunch either as a bluff or by actual knowledge causing LHO to alter his story. Ultimately he places himself as being alone and working upstairs until two verifiable encounters took place.
In todays world the request for an attorney would have ended the interview. Back then it does not appear to have mattered.
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The use of the word "vestibule' also seems to take Belin back. You can tell by his reaction. Because of a Catholic upbringing I immediately thought of the area prior to entering the church itself. Outside doors, a space(vestibule), and then more doors to the church. I also thought it was an odd way to describe it. Holmes did not seem to particularly agree with the use either.
The key to the Coke story is not LHO drinking one , but that he was physically standing by the machine itself when he was talking to Baker. That can only be accomplished if he is on the second floor.
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Your vocabulary is very impressive. I was forcedd to look up the definition of uncongenial along with several others. Based on an engineering background, if you don't pay attention to the details, your newly constructed bridge just might fall into the river.
https://www.bing.com/videos/search?q=tacoma+bridge+collapse&docid=608045869369786645&mid=D8B80A1C110379BC596AD8B80A1C110379BC596A&view=detail&FORM=VIRE