First, the suggested label is BEROC_ so actually the first letters are BER and not ER.
Front side is the easier case, and it is explained in the document A&R provided prior to the DCS request. I agree with you that there should be only one ER for each lens but that is still the case, at least as I understand it. Only one ER, that can appear on the front side or the back, not on both.
Personally, I currently don't see how these labels should affect the way we engrave the OC of the lens. It should only affect the description of the measuring points location on the front side of the lens (as defined in ISO/ANSI). These points should be described with reference to the back side engravings (in case they are on the back), and that is what the new suggested system is trying to define.
As you described, there is a chance that we missed the mismatch with some old labels. I pass your notes to our algorithm team for review. I will definitely share their conclusions when ready. Maybe we can have a phone call to exchange insights on that.
Thanks a lot for your notes and hope to see you in the next convention as well.