Numerous Vendors might send a Publisher the same ads.txt line(s), resulting in duplications in the ads.txt file. The duplication may expose the Publisher to risk. As in most cases, at least one of the Vendors is not representing the "duplicated Seller" directly but via a third party, allowing unauthorized reselling of the inventory. Duplicated ads.txt lines can often occur due to an honest mistake of "copy-paste." In either case, remove unnecessary lines, as it signals a poorly maintained ads.txt file.