An apparatus (100) recognizes user identifying data, stored in a support, for joining the support to a document containing personal information. A plurality of reading devices (12) read and recognize the data stored in each support (11). A work unit (L) has a work surface (1) on which the reading devices (12) are placed, the work surface (13) rotated to convey angularly the reading devices (12), so that each of them is placed subsequently in a position corresponding to a first section (S1) and to a second section (S2) of the work unit (L). First conveying means (T1) convey the supports (11) to a respective reading device (12). Second conveying means (T2) then convey the supports (11) from the reading device (12) to a section (20) of a feeding line (A), so as to join the support (11) to corresponding documents (D), fed to the section (20).