1) backs were produced ouside Omega .. so a back punched " 1964 " doesn't necessary means that the watch has been " assembled " (= produced ) in the very same year ( something we have also in Rolex watches)
2) as with Rolex .... the swap between a model and the following one takes some time ( from months to an year or .... ) : 165014 and 165024 lived side by side for 2 years at least.
I wouldn't even be surprised to see a 165014 produced at the beginning of 1967 ....