My apologies if this has been discussed before, but I couldn't find it listed anywhere.
I just wanted to ask about the card numbering sequence of the entire collection.
Is there a reason behind each group of cards having a different prefix letter? (A, C, E, F, (D))?

I realise the earlier edition of cards are mostly all start with A, but all the newer ones are either E or F
Then some of the Duo couple cards are in the C group, with a blue background on those cards.

Hoping to get a clear understanding behind the grouping of cards. Thanks.

An answer from almost exactly a year ago

https://www.istripper.com/forum/thread/43837/1?post=647327

Уголок новых участников / Number of cards in the store

There are different collections in the iStripper line up and these have arisen over time The Collections are identified by the letter prefix A through to I and are as per the attached pic as at 10th J...