4x4 Action Group

are there any legal implication for one as in photo?
wired to work only when reverse gear is selected.

Not as far as I know. As long as there are not more than 2.

175. Reversing lamps
(1) A motor vehicle may be fitted with a reversing lamp emitting a white light, which
illuminates the road to the rear of, or under the vehicle.
(2) Such a lamp shall be under the direct control of the driver and shall be either so fitted as to
operate only when the motor vehicle is placed in reverse gear or be connected with a device by which
the driver shall be made aware that the lamp is in operation.
(3) Not more than two such lamps shall be fitted to a vehicle and no light shall be emitted
therefrom except when the vehicle is reversing or about to reverse

mahindra is originally equipped with only one.
so im safe.thanks.

The electrics on Indian vehicles are not known for being robust, so soon you'll only have the new one.