IND CS 6: Duplicating images makes them look "lighter"?

Hello

ever since updating to CS6 my Indesign behaves strangely when handling pictures:

Once I duplicate a picture, it seems to loose some of it's saturation, thereby noticably looking "lighter".

This happens with copy/cut paste and alt+drag as well.

Re-embedding the pictures helps, but with 500+ pictures in a document, this is rather painful.

Unfortunately, the phenomenon persists all the way into the final pdf I export for printing.

I tested with both CMYK and RGB Jpgs, Psd & Tifs, with Effects (Multiply) on them and without, the same behavior everywhere.

Here's a screenshot of a duplicated image on top of the original:

I really don't know what it could be, any ideas?

My System is a 15" MacBook Pro with the latest version of Lion running (no Mouintain Lion), and the CS6 is up to date.

Thanks a lot for any input!

Best

L