The lower numbers are production-lot-numbers. The last series of 40DCOE2's were used on 2L in Europe, and as replacement Webers for any application calling for (in this case) a DCOE2. Those are just a pair of final series 40DCOE2's from the same production lot. They will also have steel butterfly bars and other developmental upgrades as compared to earlier variations. You will see these lot numbers in the serial number area of many DCOE final variations.
Usually, when bought from a supplier, it was unusual to find a pair from the exact same lot together, more often seen would be a 0C and a 2C or 0D for example. This is true even of the cars assembled using this final series.
My opinion is from my experience. I just finished (moments ago) the restoration of a pair of 40DCOE27's, one 6E and the other 7F for a customer.