MacBook Pro 15" A1226 wrong serial number

My MacBook Pro 15" A1226 shows up with a wrong serial number. This serial does NOT match the Modell, it shows up as a newer unibody model from 2009.

The serial printed inside the battery cavity DOES match as a 2,2 Ghz, ( original) 2 GB RAM, 128 MB NVRAM nVidia graphics model.

I am aware of the fact that the upper case or logic board are swapable.

You could change the serial with the blank board serializer but only when it is blank and not already having a number.

maybe this is a side effect with a non-charging battery or a malfunctioning PRAM chip?