Well this wasn’t my day today. I Imported an archive.pst file into my inbox THREE times. and now I was sitting there and had to pick out the duplicates.
It took me something like 4 hours to finaly find a tool that was able to help me. And because I want you to not look around for so long here the link to the tool
Sadly it only deletes the duplicates in the current folder. But it is still better then nothing.