I don't know about TWUNK, but TWAIN is the standard interface for scanners ' nearly all scanners come with a TWAIN driver, which makes them compatible with any TWAIN-supporting software.
TWUNK files are associated with TWAIN files. If you wish, you may delete them safely. Take a look here: http://www.google.com/search?q=twunk+twain&hl=nl&newwindow=1