My solution,

1-first you must fill of the form name property i prefer with scx name
2-add a property to the form which is name isSingleRun value with .t.
3-put below codes to load event of the form

LOCAL x,nFormCount
nFormCount=0
IF this.isSingleRun
	FOR x=1 TO _screen.formcount
		IF _screen.forms(x).name==this.Name
			nFormCount=nFormCount+1
		ENDIF
		IF nFormCount>1
			_screen.forms(x).show() 
			RETURN .f.
		ENDIF
	NEXT
ENDIF