Is using the same id multiple times on a page bad practice even when I am not parsing through the page?

Question

I understand that using the same id multiple times in a page creates malformed html. When using a jquery selector only the first element with the id will be returned, but in

Answer 1

http://www.w3.org/TR/WCAG20-TECHS/H93.html

http://www.w3.org/TR/html401/struct/global.html#adef-id

There are other things that read your HTML document, not just browsers.

According to the HTML specification, the id attribute MUST be unique on a page (it's not a criteria web designers/developers just invented)