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Quite possibly on a ring main protected by a 32amp breaker if it's in a kitchen. A ring main consists of 2 twin & earth cables (usually 2.5) which gives the cables a higher capacity due to ohms law etc...
The total max load in your case is 3.5kw/240v=14.5A
That probably falls within safe limits based on diversity and over engineering. The cable and breaker are likely rated for at least 16A, sockets 13A draw in each 'gang'.
Cheers. Switching the single socket for a double seems sensible then. It's for a washer/dryer (2.2kw) and microwave (1.3kw).