Duplicate element ID renders invalid HTML

There are pages where you come across multiple form submit buttons, for example pages with both a search box and a comment options form, like the following:

http://drupal.org/comment/reply/270093

In the page code above you have

line 38:
<input type="submit" name="op" id="edit-submit" value="Search" class="form-submit" />

line 96:
<input type="submit" name="op" id="edit-submit" value="Post comment" class="form-submit" />

where "edit-submit" is not unique.

Hope this will be fixed in future drupal releases…