Whether that's ok will depend on the size of the cooker fuse/circuit breaker, and how the existing cable is run.
A simpler way would be to avoid using 6mm cable at all.
I guess you have a cooker switch above worktop, and an outlet connection below worktop level?
Either replace the outlet connector with a double socket, or two fused spurs.
What size is your existing cooker fuse/breaker?



