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If you are 100% confident that the ring is sound and you aren't spurring from a spur then you can add one spur socket from each ring socket.
But... And here is the caveat, if you don't know you need to test or have an Inspection Report that tells you how it's wired currently at the moment.
It IS an addition to a circuit so 'legally' you would need a Minor Works Certificate to be kosher.
They will go back into the CU together but will split somewhere to form a 'ring' (unless there is some reason not to). If its all in conduit they probably sent L/N/CPC to each socket in order and just did one long length back again.
The pictures are meant to be simplistic to show the wiring connections rather than real-world installation.
The sparks will do a ring final circuit test to make sure the right set of wires of the two pairs are connected to the right sockets.
If you have swapped pairs or breaks in the ring circuit it can be fixed.