When you set digital File Pro to upload multiple copies of a file to different folders, there are Server File name bindings created in the WA Uploaded Files (File Filed name) bindings group.
Say for example that I have a Thumbs and Large folder that I am uploading to, the Bindings groups will contain bindings titled:
Thumbs[FileName]: Server File Name
large[FileName]: Server File Name
For the database column you wish to store the thumbnail in, bind to the Thumbs[FileName]: Server File Name, for the column you wish to store the large image name, use the large[FileName]: Server File Name binding.