That’s right… it’s been a while. I assumed that since there were two elements with the same ID it would return an array. Dangit, jQuery, yer screwing up my method of thinking!!!
I should have used document.formname.customertype[0] and document.formname.customertype[1].
According to jQuery, the selector returns a jQuery object which, I believe, is at least array-like, if not an array. So $('[name=customertype]').each() will iterate through an array (or array-like jQuery object) and conduct whatever instructions are within the () of each.
The jQuery object internally uses an array to store the elements (and applies every operation on that array). But even then jQuery only selects one of the multiple elements (since it internally uses getElementById() for that case).
If at all possible, serve one of them with a checked attribute from the backend depending on the request. Otherwise @WolfShade’s approach would do the trick (going with the name though – IDs must of course be unique). ;-)