diff --git a/Tools/idle/IdleHistory.py b/Tools/idle/IdleHistory.py
index 3094173..aa41b73 100644
--- a/Tools/idle/IdleHistory.py
+++ b/Tools/idle/IdleHistory.py
@@ -2,11 +2,12 @@
 
 class History:
 
-    def __init__(self, text):
+    def __init__(self, text, output_sep = "\n"):
         self.text = text
         self.history = []
         self.history_prefix = None
         self.history_pointer = None
+        self.output_sep = output_sep
         text.bind("<<history-previous>>", self.history_prev)
         text.bind("<<history-next>>", self.history_next)
 
@@ -18,16 +19,26 @@
         self.history_do(1)
         return "break"
 
+    def _get_source(self, start, end):
+        # Get source code from start index to end index.  Lines in the
+        # text control may be separated by sys.ps2 .
+        lines = string.split(self.text.get(start, end), self.output_sep)
+        return string.join(lines, "\n")
+
+    def _put_source(self, where, source):
+        output = string.join(string.split(source, "\n"), self.output_sep)
+        self.text.insert(where, output)
+
     def history_do(self, reverse):
         nhist = len(self.history)
         pointer = self.history_pointer
         prefix = self.history_prefix
         if pointer is not None and prefix is not None:
             if self.text.compare("insert", "!=", "end-1c") or \
-               self.text.get("iomark", "end-1c") != self.history[pointer]:
+               self._get_source("iomark", "end-1c") != self.history[pointer]:
                 pointer = prefix = None
         if pointer is None or prefix is None:
-            prefix = self.text.get("iomark", "end-1c")
+            prefix = self._get_source("iomark", "end-1c")
             if reverse:
                 pointer = nhist
             else:
@@ -40,15 +51,15 @@
                 pointer = pointer + 1
             if pointer < 0 or pointer >= nhist:
                 self.text.bell()
-                if self.text.get("iomark", "end-1c") != prefix:
+                if self._get_source("iomark", "end-1c") != prefix:
                     self.text.delete("iomark", "end-1c")
-                    self.text.insert("iomark", prefix)
+                    self._put_source("iomark", prefix)
                 pointer = prefix = None
                 break
             item = self.history[pointer]
             if item[:nprefix] == prefix and len(item) > nprefix:
                 self.text.delete("iomark", "end-1c")
-                self.text.insert("iomark", item)
+                self._put_source("iomark", item)
                 break
         self.text.mark_set("insert", "end-1c")
         self.text.see("insert")
@@ -59,6 +70,11 @@
     def history_store(self, source):
         source = string.strip(source)
         if len(source) > 2:
+            # avoid duplicates
+            try:
+                self.history.remove(source)
+            except ValueError:
+                pass
             self.history.append(source)
         self.history_pointer = None
         self.history_prefix = None