Term in
broadcast news for a graphical overlay on the screen with two rectangular "holes" where two separate
video sources are inserted. A double box is typically used for two
live shots from different locations, with a conversation taking place between the participants; i.e., an
interview, or a dialog between a remote
reporter and an
anchor in the studio.
The double box graphic is created and controlled from a character generator, such as a Chyron or Deko. The video sources are then mixed together by a switcher for play to air.
According to non-US noders, the double box is unique to US news and is unlikely to be seen outside of the States.