Do you mean two blacks and two reds?
or two browns and two blues?
If not your conductor colours have been installed wrong.
You should have a line conductor which could be Brown or Red
A neutral conductor that should be Blue or Black.
Then a pair of cables from your switch colours again Brown or Red and Blue or Black
Lets say your cable are Red and Black.
Connect the two Reds together with nothing else.
Connect the a black this should really your switch live and tagged with brow or red sleaving to the brown side of light fitting flex, (important this is done correctly if eddison screw lamp fitting)
Connect the other black to blue side of light fitting.
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