hide the submit button on click.
change:
<input name="Add_New_Ticket" type="image" id="Add_New_Ticket" value="Add_New_Ticket" src="../images/add.png" alt="Add_New_Ticket" hspace="0" vspace="0" border="0" />
to:
<input name="Add_New_Ticket" type="image" id="Add_New_Ticket" value="Add_New_Ticket" src="../images/add.png" alt="Add_New_Ticket" hspace="0" vspace="0" border="0" onClick="this.style.visibility = 'hidden';" />