Association between ebooks in library and on reader

Hi,

I've got the following Problem. I've added two different ebooks to my library that have the same title, author and publisher but seem to have different IDs (according to the metadata and the opf file).

After moving the books to my reader (PRS-T3), both books on the reader are associated with only one of the two books in my calibre library, i.e. calibre shows that one of the two books in the library is twice on my reader.

Is there a way to correct this association so that each of the books in my library is connected with the corresponding book on my reader?

Regards,

McDummy