Systems and methods for processing sheets, statements, and/or inserts prior to mailing are provided. One sheet processing system includes a receiver adapted to receive first and second single page sheets to be processed. The first sheet originates from a stack of first sheets, and the second sheet originates from a stack of second sheets. In some systems, the first and second sheets are of different sizes. The system includes a first read head adapted to read a first identifier from the first sheet, and a second read head adapted to read a second identifier from the second sheet. A circuit coupled to the first and second read heads is adapted to compare the first and second identifiers to determine whether a match exists. At least one identifier may include a magnetic stripe.