A double print and a pseudo-double print may look similar, but they are produced in different ways. A double print results from printing the stamp design twice on the same side, while a pseudo-double print is caused by improper contact between the paper and the printing surface.

Double print

A double print occurs when an already printed sheet is fed through the press again and the stamp design is printed a second time on the same side. The two impressions usually do not register exactly, producing a characteristic and often striking doubled image. An important feature is that both impressions are genuine and normally of approximately equal strength.

Very rarely, a sheet may be reinserted into the press upside down. This produces an inverted double print.

Pseudo-double print

A pseudo-double print may resemble a true double print, but it is not caused by the sheet being printed twice. It can occur when the paper does not lie flat against the printing surface, for example because of trapped air or a developing crease. One side of the raised paper may contact the printing surface twice: one contact produces a weak impression and the other a full-strength impression. As a result, one of the doubled images is usually fainter.

Pseudo-double impressions may occur in planographic, intaglio and relief printing, but are more common on uneven paper and in intaglio processes using dampened paper.