my radio button not working properly?

Code:

<input type="radio" name="kvr"  checked="checked" onclick="hideall1();showit1('x1')"  <?php if (isset($_POST['kvr']) && $_POST['kvr']=="yes") echo "checked";?> value="yes"  >Same &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;

<input type="radio" name="kvr" onclick="hideall();showit('x1')"  <?php if (isset($_POST['kvr']) && $_POST['kvr']=="no") echo "checked";?> value="no" >Other

at first radio button click the form should not be submitted, after click second radio button  the value only be passed. why? need suggestion