As driven has said, unticking export two sided faces should handled this situation.
So i did some more tests and i have found out that my problem is my sketchup, or version of sketchup. I'm using the 2014 version and no matter what i do it messes up my export file.

I installed the 2105 and it works perfectly. I don't have a clue on why this happens, but at least i have found a way to solve my problem.

Thank you so much for your fast replies! It helped me alot.

Is there a way to apply the same material to a face and backface at the same time?

I am trying to export my object to C4D with DAE format as it is alot cleaner than the other formats, however when i merge in to my C4D it duplicates the faces because the faces have 2 materials and this creates zfighting.

Any solution? It's my last problem to fix to get sketchup + C4D working as i want and it's driving me crazy cause i can't find anything about it.