Acrobat: Font changes on paste

Using Actobat Pro CS2, I observe strange behavior to text when pasting a certain diagramm exported from Excel as PDF into the current document. This issue concerns the text already in the document, not the text in the diagramm itself. The edges around the text lose their "smoothness", thus aliasing is stronger and the text looks noticably bolder.

The texts paramters do not change, however. They remain the same typeface, size, etc.

What I tried:

• Copying the text from Document A to the one containing the diagramm


• Copying the diagramm into Document A


• Importing the diagramm into Illustrator and exported as AI, PDF and ESP upfront, before copying into Document A

I ofcourse could export the digramm to a raster format, but really want to avoid this so the diagramms labeling remains in tact (not rastered). Oh and colorspace for all documents is CMYK, for what it's worth.

Hope anybody has experience with this madness. Best Regards!