In article ,
IMM wrote:
Double dimmer (two knobs) in a double metal box: Does anyone know who
sells these? This is an elongated switch fitting into a double socket
box.

Not seen them.

Get two suitable one gang dimmers and a two gang blank plate to match the
existing fittings. Drill two holes and mount the gubbins.

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*Work is for people who don't know how to fish.

Dave Plowman London SW 12
RIP Acorn