FULL PRODUCT VERSION :
java version "1.7.0_79"
Java(TM) SE Runtime Environment (build 1.7.0_79-b15)
Java HotSpot(TM) 64-Bit Server VM (build 24.79-b02, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Windows 8.1 64bit

A DESCRIPTION OF THE PROBLEM :
If I insert a record with:
key "02" and value "XXXX"
key "11" and value "XXXX"

The last key "11" replace the Entry with key "02"

Attention: after to string appear all maps with correct value, but If you do a for or use the debug appear a different situation.

REGRESSION. Last worked in version 6u45

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Debug the source code in attachment

ACTUAL -
Debug or for show all value except "02" (because It's replaced by "11")

ERROR MESSAGES/STACK TRACES THAT OCCUR :
no exceptions

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------

import java.util.HashMap;
import java.util.Map;


public class Main {

public static void main(String[] args) {

Map<String, String> maps = new HashMap<String, String>();

maps.put("01", "be54btr");

maps.put("02", "be54bertr");

maps.put("03", "beh54btr");

maps.put("04", "be546btr");

maps.put("05", "be544btr");

maps.put("06", "be54bjtr");

maps.put("07", "beshbtr");

maps.put("08", "bekkkktr");

maps.put("09", "be5sssbtr");

maps.put("10", "be235235tr");

maps.put("11", "be5475vvvbtr");

maps.put("12", "ccc475vvvbtr");

maps.toString();

}

}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
(only for String Key)
Check each char into old and new key.