You are looking at a "Library Loading Report"
that says you have two identical library parts
stored in two different folders of your loaded libraries.
If you scroll over to the right in the loading report
it will tell you where each is stored.
If you want to not have the error report,
you will have to remove one of the duplicates.
To do this correctly, please read this thread carefully
and follow the advice given.
http://archicad-talk.graphisoft.com/viewtopic.php?p=87700&highlight=lcf#87700
Peter Devlin