This isn't really an "authenticate" question, just something I was curious about. I came across a seller who had the same bag in many colors and noticed that in her listings she showed a close up of the tag. Each tag had the correct color name but the exact same color code number on each tag... I found this off since I know each color name has a specific color code... should I consider this a red flag ? Feel free to PM me about it.
I don't really pay any attention to tags unless they are really off. Sometimes retailers like Nordstrom and Bloomie's get a run of bags where something is wrong on the tag but the bag is otherwise in perfect condition. What I would be wary of is if a seller has the many of the same style in the same color. Very few sellers on ebay/Tradesy/Poshmark will take the risk of carrying 20 of the same color York tote or anything along those lines.