Recommendation: Tool for import files/folder - that doesn't duplicate duplicates

I need help finding a way of archiving my photographs. My requirements are very few:

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  I want to copy/move a set or files or a folder into my photos-folder where i have subfolders named "yyyu-mm-dd" (=EXIF date taken)

  
  


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  When doing this, the tool needs to avoid importing the same photo twice (Like with Acdsee: The second time I import the same image it adds " (1)" to second files name, then " (2)" to the third and so on...)

  
  


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  Should work in Windows or Linux. Preferably Windows.

  
  


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  Would be nice to be able to select a set of files to import rather then a whole folder.

  
  
  

I used Adobe Lightroom for a while but it was too expensive for this simple task. But I liked it. I could just select a couple of files in windows and drag'n'drop them into Lightroom and the importer would pop up and it didn't import duplicates and so on. So simple.

After that I switched to Acdsee. Liked it a lot but the import UI feels a bit behind and cumbersome. It didn't handle duplicates in a good way, as i mentioned before. Have a missed any configuration for this?

Using the windows build-in photo-importer can only import files from a camera, not a folder or a selection of files.

Can you recommend a tool for this that is either not as expensive as Lightroom or open source?