Index: lams_tool_sbmt/src/java/org/lamsfoundation/lams/tool/sbmt/SbmtResources.properties
===================================================================
diff -u -r7ce5a98708f5a561d46682de26ae44541ab23d20 -rc125a5450d5e6766f697382a1e5c1abb5c7e933e
--- lams_tool_sbmt/src/java/org/lamsfoundation/lams/tool/sbmt/SbmtResources.properties	(.../SbmtResources.properties)	(revision 7ce5a98708f5a561d46682de26ae44541ab23d20)
+++ lams_tool_sbmt/src/java/org/lamsfoundation/lams/tool/sbmt/SbmtResources.properties	(.../SbmtResources.properties)	(revision c125a5450d5e6766f697382a1e5c1abb5c7e933e)
@@ -30,6 +30,7 @@
 #-------------------------Exception Labels-----------------#
 sbmt.web.action.upload.exception = Upload of file failed.
 
+submit.upload.twice=You already upload this file, please waiting for a while.
 
 # Errors
 learner.from.filepath.displayname=Upload file name
Index: lams_tool_sbmt/src/java/org/lamsfoundation/lams/tool/sbmt/web/LearnerAction.java
===================================================================
diff -u -rdf1375bbde992f59d04ee895a971eb4dfa7282b1 -rc125a5450d5e6766f697382a1e5c1abb5c7e933e
--- lams_tool_sbmt/src/java/org/lamsfoundation/lams/tool/sbmt/web/LearnerAction.java	(.../LearnerAction.java)	(revision df1375bbde992f59d04ee895a971eb4dfa7282b1)
+++ lams_tool_sbmt/src/java/org/lamsfoundation/lams/tool/sbmt/web/LearnerAction.java	(.../LearnerAction.java)	(revision c125a5450d5e6766f697382a1e5c1abb5c7e933e)
@@ -54,6 +54,9 @@
 		submitFilesService = SubmitFilesServiceProxy.getSubmitFilesService(this.getServlet().getServletContext());				
 		List filesUploaded = submitFilesService.getFilesUploadedByUser(userID,sessionID);
 		authForm.set("filesUploaded",filesUploaded);
+		
+		//to avoid user without patience click "upload" button too fast 
+		saveToken(request);
 		return mapping.getInputForward();
 		
 	}
@@ -63,6 +66,10 @@
 									HttpServletRequest request,
 									HttpServletResponse response){
 		
+		if(!isTokenValid(request,true)){
+			return returnErrors(mapping,request,"submit.upload.twice","upload");
+		}
+		
 		DynaActionForm authForm= (DynaActionForm)form;
 		
 		Long sessionID =(Long) authForm.get("toolSessionID");