On a photocopier
or computer printer
refers to the ability to print on both sides
of each piece of paper
. Most often, this is done by printing one side, shunting
the paper into a special tray
unit, shunting it back in such a way that the other side is up, then printing the other side.
Because the addition of a duplexer increases the complexity of the printer's paper path, it slightly increases the chance of a paper jam. However, printing in duplex cuts in half the amount of paper you need to print your documents. Save a tree -- print in duplex.
can also be a house
made of exactly two apartments
. The apartments in a duplex are frequently substantially identical
; sometimes they are mirror images
of one another.