a <#stamp> printed on two layers of paper.  There are two distinct causes of double paper: 1.) a double paper was intentionally used on some stamps by the <#cbnc=Continental Bank Note Co>. in the course of printing its <#largebn=Large Banknote> stamps of 1873.  2.) double paper resulted on some <#rotpress=rotary press> stamps when a tear or cut in the <#web> was repaired with a <#splice>.  Splicing required some overlapping of the <#web>, hence creating a double paper variety.  Double paper varieties were also created when two webs were attached to each other.

a <#stamp> or multiple stamps with an extraneous row of <#perf=perforations>; These are <#freak=freaks>, not <#error=errors>.

a <#stamp> that has passed through the press twice.

a <#platevar=plate variety> in which a portion of the <#design> is doubled, that is, it appears twice.  A double transfer occurs on <#engraving=engraved> stamps when a design is "<#rocking=rocked>" into a <#plate> from a <#tranroll=transfer roll> in such a way that the rocked images are out of alignment.  Thus, if the <#siderographer> is not careful, the rocking in of the design will cause a part of the design to appear more than once.  Sometimes a double transfer on a <#plate> is discovered and is "<#burnish=burnished>" out.  But if this process is not totally successful, some amount of doubling of the design may remain.  All sheets printed from a plate with a double transfer will show the double transfer.  Thus, the double transfer will be a <#constvar=constant variety>.

a letter deposited at a post office for delivery to another patron at the same office.  Drop letters were sometimes charged less than letters requiring dispatch to a different post office.  See also: <#localletter=Local Letter>.