3/16/2011 5:52:20 AM
RE:Update file in media library updates create date AND modified date
Please note this behavior is correct and by design. When you update document, new document is uploaded, since you can choose any document with "update" option.
So, technically, new document is uploaded, therefore FileCreatedWhen is updated as well.
Situation, when FileCreatedWhen stays on original value, and FileModifiedWhen is updated, is when you modify some file e.g. in Image editor. Then, file is really just updated, however when using "update" functionality, file is uploaded again = it is a new file.