If you have multiple of the same name with the checked attribute it will take the last checked radio on the page.
<form>
<label>Do you want to accept American Express?</label>
Yes<input id="amex" style="width: 20px;" type="radio" name="Contact0_AmericanExpress" />
maybe<input id="amex" style="width: 20px;" type="radio" name="Contact0_AmericanExpress" checked="checked" />
No<input style="width: 20px;" type="radio" name="Contact0_AmericanExpress" class="check" checked="checked" />
</form>