Yes, the referencing system changes make this a confusing period. What is interesting to me, Dean is that the Dual Time version you show above (from what year?) has the PDLF laurel engraved on the back. I had assumed that only the first series of watches produced in 1972 might have come with this engraving.
This image from Secrets of Vacheron provides a concise, albeit incomplete, summary of the 1972 (note all three listed as ladies watches):
This one from an Anitquorum Catalogue appears to be a smaller, ladies version, and note the 5-digit reference number!
To add to the confusion, this example from Treasures of Vacheron Constantin indicates that the caliber is1052. The description is also interesting in that it describes the original series as a limited edition accompanied by a special lithograph by Jean Carzou. Wouldn't it be something to find a complete set with the watch and the lithograph?!?!?
I am willing to bet that the dual time PDLF has a double movement as the following two non-PDLF references do (also from Treasures of Vacheron Constantin):