Will RazorERP track back product that may get a case (return or resolution) on eBay or Amazon?

Yes, there is always an RMA that is generated for every product that is returned and that unique serial item would get tracked back to the RMA that is generated. If the buyer returns a product with a different serial number you can make a strong case for illegitimate return reasons on behalf of the buyer and report them since you have all the data available to you.