probaly the problem was that the script uses submit button name to decide what to do.
something like that:
<form action=test.php method=post>
<input type="text" name="val" value="<? echo $val;?>"><br>
<input type="image" src=image/some.gif name="first" value="lala" border=0>
<input type="image" src=image/some.gif name="second" value="lulu" border=0>
</form>
<?
if ($first_x){
echo "first";
} else if ($second_x){
echo "second";
}
?>
note, use VARNAME_x - php split var name to x and y