diff --git a/src/backend/utils/misc/guc-file.l b/src/backend/utils/misc/guc-file.l
index 7d30105..785631e 100644
--- a/src/backend/utils/misc/guc-file.l
+++ b/src/backend/utils/misc/guc-file.l
@@ -562,7 +562,9 @@ ParseConfigFp(FILE *fp, const char *config_file, int depth, int elevel,
 	{
 		char	   *opt_name = NULL;
 		char	   *opt_value = NULL;
-		ConfigVariable *item;
+		ConfigVariable *item,
+					   *cur_item = NULL,
+					   *prev_item = NULL;
 
 		if (token == GUC_EOL)	/* empty or comment line */
 			continue;
@@ -645,7 +647,10 @@ ParseConfigFp(FILE *fp, const char *config_file, int depth, int elevel,
 		}
 		else
 		{
-			/* ordinary variable, append to list */
+			/*
+			 * ordinary variable, append to list.  For duplicate items,
+			 * retain only which comes later.
+			 */
 			item = palloc(sizeof *item);
 			item->name = opt_name;
 			item->value = opt_value;
@@ -655,7 +660,37 @@ ParseConfigFp(FILE *fp, const char *config_file, int depth, int elevel,
 			if (*head_p == NULL)
 				*head_p = item;
 			else
-				(*tail_p)->next = item;
+			{
+				/* Remove the item if it already exists in list */
+				for (cur_item = *head_p; cur_item; prev_item = cur_item,
+					 cur_item = cur_item->next)
+				{
+					 if (!strcmp(item->name, cur_item->name))
+					 {
+						 if (prev_item == NULL)
+							 *head_p = cur_item->next;
+						 else
+						 {
+							 prev_item->next = cur_item->next;
+							 /*
+							  * On removing last item in list, we need to update tail
+							  * to ensure that list will be maintianed.
+							  */
+							 if (prev_item->next == NULL)
+								 *tail_p = prev_item;
+						 }
+
+						 pfree(cur_item);
+						 break;
+					 }
+				}
+
+				/* if the only item in list got deleted, then update head */
+				if (*head_p == NULL)
+					*head_p = item;
+				else
+					(*tail_p)->next = item;
+			}
 			*tail_p = item;
 		}