Ha!
Not just me who has trouble then!
I'll admit to recently spending a few baffling minutes trying to work out why an image from my 5DII was looking quite noisy at ISO 3200; a sure sign I mucked up the exposure and tried to recover it in Lightroom.
But I couldn't work out which slider I'd lent on too hard.
Eventually it dawned on me that it was an X10 image

Thank goodness the RAW file extension is different; saves diving into the meta data to check which is which.
This problem is less likely to happen in the future as my 5DII is going to be regularly paired with the 135mm f2.
The image quality out of that lens is unmistakable, even on a 6"x4" print.
Dive into my Jubilee Gallery and you will see what I mean.
http://www.wild-landscapes.co.uk/Blog/2012-06-03-Jubilee/