Duplex cancel

A duplex cancel consists of two parts, a CDS or similar postmark plus a killer/obliterator.

This handstamped cancel can be struck by a device with both parts permanently together. There are versions where the killer is removable to allow cancellation of multiple stamps.  File:Duplex cancel.png|striking end of an RMS cancel hammer. Note spaces and slugs that allowed changing data including the trip number. File:US New Orleans postal card.jpg|US New Orleans duplex on 1893 postal card to Germany. 

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