We have old proprietary RFID tags on library materials, and plan to re-tag using a standard model. Will the presence of the prior tags interfere with the performance of the new ones?
There should be no interference, provided that the new tag's antenna does not touch that of the old tag, or is not located beneath it. If, for instance, you were to place the old tag on a book's inside cover and the new one on the first page, and if the old tag covered the new one when the book was closed, it could block radio waves from reaching the new tag's antenna. Other than that, I see no problem.
—Mark Roberti, Founder and Editor, RFID Journal