AdWords API Duplicate keyword quota issue

If I add a keyword that already exists in an Adgroup am I charged 50
quota units?

I ask this because my code currently reuploads 50 or so keywords on a
periodic basis. I don't worry about dupes. I just upload all the
keywords and Google currently appears to ignore duplicates.

But if I am charged for duplicates, then I will need to write a new
script that looks for existing keywords and eliminates dupes prior to
uploading.