2 watch, same individual number?

They aren’t the same individual number though. Examples that left the production line together would have the same iteration number (barring the last and first of each I guess). As above the serial will tell more. These watches could be years apart.

It represents some change known usually only to the factory, perhaps a design change or change in supplier for the case or other components. In Omega circles it doesn’t usually have a bearing on the dial design, though it can on some models like the Speedmaster. This is a Longines so there may not be a direct carry across but be aware that the early 50s Omega model 2577 (made for around 7 years) had at least 22 iterations and there isn’t a discernible pattern as to why. 2 fat lug Seamasters with the same iteration can have totally different dials. Perhaps they made a batch of watches and then moved onto another style and incremented the iteration for each batch.