A duplicating machine, particularly for punched keys and laser keys, comprising on a base (14) two clamps (86, 88) for an original key to be duplicated and for a blank key to be cut, and a carriage (18) movable vertically relative to said clamps and supporting, by means of self-centering chucks (56, 34), a feeler (28) above the original key and a cutter (26) above the blank key, the height of said feeler (28) above its clamp being adjustable independently of said cutter (26), characterised in that: said self-centering chucks (56, 34) are electrically insulated from the machine body and are connected to one terminal of a respective indicator member (78, 78') the other terminal of which is connected to an electrical power source (84); said self-centering chucks (56, 34) are also connected to two inputs of a logic coincidence circuit (85) the output of which is connected to one terminal of a third indicator member (64), the other terminal of which is connected to said electrical power source (84); the self-centering chuck (34) for the cutter (26) is associated with a threaded shaft (36) which is rigid with an operating knob (38) and is housed within a tubular support (42) comprising at least one radial cavity (48) engageable by a radial pin (50) movable axially relative to the structure of said carriage (18) and operable from the outside for its engagement movement.