By Etsy rules, it is NOT acceptable to only answer one of the messages from a buyer, even if it is a duplicate. Etsy is currently grouping messages from the same buyer into a single thread and posting a warning on messages that need a reply, but like many Etsy features, this is not foolproof. The rules say EVERY new message received must be answered within 24hrs or marked as spam. You can create a snippet for use on duplicate messages that just says "answered in your other message" or similar, and it only takes 3 clicks to select the snippet, apply it and send the message. Alternatively, in one click you can mark the duplicate as spam and it won't count.
Star Seller is calculated on the previous 3 months of sales. Messages "almost 3 months ago" still count for the Nov 1 allocation, but will drop off for the Dec 1 allocation. It is too late to mark the duplicate as spam this time around, the last 24-48 hrs are the processing zone and actions taken within that time will probably not be picked up in this month's assessment. Etsy won't adjust manually after the assessment begins, but those older ones will not count toward next month anyway.
