All of the lathes sold by Sears that were made by Atlas Press Co. have Model Numbers that begin with "101". "101" is the Sears Contractor Code for Atlas Press. "109" is the Contractor Code for AA.
"Dunlap" (not "Dunlop") is a Sears badge name, like "Craftsman", "Kenmore", etc., not a contractor's name. It was in use in the early 40's when the 6x18 model 109.0702 and 0703 were being made. By 1948 when Sears again started selling a lathe made by AA, they had all become 6x12's and were called Craftsman "80", not Dunlap.
"618" is the model number that Atlas assigned to all of the Atlas badged 6x18's that they made. They also called their 6x12 "612". The Sears badged ones have Sears model numbers. The 101.07301, made by Atlas and sold only by Sears has several things different from the 618 of the same vintage. The most obvious ones being sleeve spindle bearings and a 1"-8 spindle nose thread. All of the Atlas 618's have 1"-10 threads. It is a not uncommon mistake to call all 6x18's "618". The mistake is probably what lead to the Internet disinformation that early 618's had 1"-8 threads.