No preference, and it doesn't sound like something useful to enough people to make it worth the effort of implementing. (I could be wrong, Kovid would be the one to say. But IIRC it has been brought up before.)
@BetterRed has mentioned a few times an interesting way of keeping track of all kinds of duplicated content and extra info, by adding a link to a folder on the hard drive which contains extra stuff. You can stick the link in the comments field, and it should be in the format
Code:
file:///DRIVELETTER:/path/to/special/folder/