Abstract: Polymodal magnetic information-recording articles formed with at least two different populations of magnetic powders, whereby at least one of the powders, being of lower intrinsic coercivity and forming means to accept a noise interference pattern, accepts a pattern which serves as a means to verify the authenticity or detect previous tampering with the magnetic recording device. More generally, the disclosure relates to polymodal recording media characterized by incorporation of a plurality of independently - erasable ferromagnetic powder populations and processes for making and using said media.