It depends on the location. Kitchen - no. Detached garage/shed/etc - no. Bathroom (now allowed under certain conditions) - no.
Wherever it is you will need certain competances to be able to do it safely.
You can buy single to double fittings that dont require any messing. They simply fit to the old single back box so i dont see any problem as you are not altering the wiring. This is supposing the wiring is in good condition.
If you need to find a tradesperson to get your job done, please try our local search below,
or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Please select a service and enter a location to continue...
Are you a trade or supplier? You can create your listing free at DIYnot Local