select2 integration -Duplicate(selected) value are appear in drop down box

[Madasamy mcruncher]

we are using select2 version 2.0  in our application.
Select2MultiChoice field are using for select a multiple value. here we set
the
"maximumselectionsize" is 20. and set "minimuminputlength" is 1.when we
give input in that field the relevant value are appear in drop down box
correctly,
if selection count reach  15 or 16, hence we give input in that field the
duplicated
(selected) value are appear in the drop down box.

but i could not recreate this problem in Myquickstart.

the sample code is

        Select2MultiChoice<Foo> fooField = new
Select2MultiChoice<Foo>("message",
              new PropertyModel<Collection<Foo>>(this, "foo"), new
FooProvider);
        fooField.getSettings().setMinimumInputLength(1);
        fooField.getSettings().setMaximumSelectionSize(20);
        fooField.setRequired(true);
        return fooField;