jquery conflicting with jquery

i want to use both jquery script in php page but both jquery script are conflicting to each others

here my code

<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js"></script>
<script type="text/javascript" src="topslider/lib/jquery.jcarousel.min.js"></script>

Conflicting Jquery Script

<script src="http://code.jquery.com/jquery-1.8.3.js"></script>
<script src="http://code.jquery.com/ui/1.10.0/jquery-ui.js"></script>
 <script>
  $(function() {
  $( "#datepicker" ).datepicker();
  });
  </script>

Copyright License：
Author:「user2115124」,Reproduced under the CC 4.0 BY-SA copyright license with link to original source & disclaimer.
Link to：https://stackoverflow.com/questions/15154067/jquery-conflicting-with-jquery