radio_button can generate duplicate id attributes (invalid HTML)

Possibly related to #2937 id for radio_button behavior.

Sometimes, radio_button can generate duplicate id attributes.

Suppose you have this ERB:

<%= f.radio_button :winner_accepted, 1 %>
<%= f.radio_button :winner_accepted, -1 %>

You get this HTML:

<input id="nominee_winner_accepted_1" name="nominee[winner_accepted]" type="radio" value="1" /> 
<input id="nominee_winner_accepted_1" name="nominee[winner_accepted]" type="radio" value="-1" />