Function  46h   Force Duplicate of a Handle (FORCEDUP or CDUP) 
		Forces handle in CX to refer to the same file at the same 
		position as BX 
entry   AH      46h 
	BX      existing file handle 
	CX      new file handle 
return  CF      clear   both handles now refer to existing file 
		set     error 
		AX      error code (4, 6) 
note 1) If CX was an open file, it is closed first 
     2) If you move the read/write pointer of either file, both will move 
     3) The handle in BX must be open