No, I don't mean memory usage (or what is "244 k")... I mean the PID column - which is kinda random ID number a process gets associated with when it starts.
Normally, the sf.bin process runs only shortly (a few seconds at most). So, my question is if those four sf.bin processes you see are "fixed" - their PID doesn't change, or if it changes every few seconds (which would mean the processes exist and new ones are started).
It might also be helpful to get
Process Explorer, select the sf.bin process in the list, press Ctrl+H and scroll to the "File" handles in to lower pane - to see what file is opened (and whether all of those sf.bin processes have opened the same scanned file).