I always use the brown of the 3 core in the common and dont really give a monkeys which others go where.
Yes it will work either way, but it is far more professional to keep L1-L1 and L2-L2, this then means if both switches are in the same position (both 'off' or both 'on'), then the light is off. If the switches are in differring positions, the light is on.
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