While performing a 'Before Landing' Checklist on a B737-800; a Captain and First Officer noticed the First Officer's Master Warning Annunciator panel 'six-pack' lights had identical verbiage displayed as the Captain's 'Recall' Annunciator 'six-pack' panel. Lettering for individual annunciator lights on First Officer's panel should be different than Captain's panel.

Narrative

During descent; we discovered the First Officer's Master Recall system light cover ('six-pack') was incorrect for the assembly. As 'Recall' was pressed in conjunction with the Descent Checklist; the verbiage on the First Officer's recall system displayed identical to the Captain's recall lens cover. After gate arrival; the Captain reviewed the Logbook and found the assembly had been replaced [days earlier]. Maintenance was summoned and attempted to swap the [lens] light cover with the proper lens for the First Officer's side; however upon installation of the replacement [lens]; the assembly would not illuminate. Further investigation revealed the [electrical] socket assembly installed earlier; although bearing the appropriate Manufacturer's Part Number (according to the Mechanic); was in fact a Captain's socket assembly (left side) and would work with a First Officer's lens cover (right side). The pins on the lens were left/right side socket specific. The incorrect installation was not readily discernible to flight crews since all twelve Annunciators on the 'six-packs' would illuminate and apparently function normally. Only by reading the lettering on the lens was the error identified.