Canon 10D User Guide (en)

You can display and handle a RAW image and JPEG image shot 
simultaneously as a single image. In particular, you can halve the 
number of images displayed in the main window and you can streamline 
the checking of a large number of images shot simultaneously.
Select the [Tools] menu   [Preferences].
Select the [View settings] tab sheet and checkmark 
[Display only CR2 images for CR2 and JPEG files of 
the same name].
The main window display updates and the simultaneously shot 
RAW image and JPEG image are displayed as a single image 
with the [
] mark 
Displaying a RAW Image and JPEG Image as a Single Image 
Images that can be displayed as a single image are images shot with a 
camera that shoots RAW images with the extension “.CR2” and JPEG 
images simultaneously. Images that have been simultaneously shot with 
a camera that shoots RAW images with the extension “.CRW” or “.TIF” 
cannot be displayed as a single image.
Image displayed
The RAW image is displayed in all windows.
Edited image
When adjustment is performed with the tool palette, only the RAW 
image is adjusted. However, deletin
, moving and copying 
 will affect both images.
RAW images with the extension “.CR2” can be displayed as a 
single image
When a single image is displayed
In step 2, if you uncheck [Display only CR2 images for CR2 and 
JPEG files of the same name], the RAW image and JPEG image 
are displayed as separate images.