I've seen this and yes there are false positives. It is unfortunate they have no reasonable appeal process. Amazon will ban you with no recourse if two selling accounts appear to login from the same network/same computer. It does not need to be a banned account. At least that's what appeared to happen in one case I've seen. Maybe it is cookies too, who knows.

Two internet merchants in the same family. Both have separate businesses, separate tax IDs, separate locations, etc. One family member is older and needs a lot of help with IT stuff. The younger family member comes over on the weekend to help with network/computer problems and happens to login and check their orders. Amazon sends an email to both of them demanding that one of the accounts be immediately closed or they will both be terminated. Again, they tried everything to get a human being to listen. No help from Amazon. The older family member closed his account and lost 50% of his revenues because he felt responsible for the entire situation. The younger seller 's account remained open. It was extremely heavy handed.

I have close relationships with both of these people and I am 100% sure neither of them are involved in any fraud.