Stop multiple radio buttons being selected

The outside and inside radio buttons need to have the same name:

<input type="radio" id="nosupp" name="supp" onchange="resetSupp(this);" value="NoSupplier">


<input type="radio" id="chk1" name="supp" onchange="change(this);" value="ADD VARIABLE SUPPLIER TYPE HERE">

Also, id attributes need to be unique. No two HTML Elements should have the same id attribute value, so using the same id in a loop won't do what you expect.

The name attribute of the HTML radio button groups them. Using the same name, but a different id, will let you find them uniquely but still group them together. By grouping them, you can make sure that only one button from a given group is checked.