What practical problem will i face if i use same #id more than one time on a page , other than validation error “ID is already defined”?

Question

First of all I alwyas use one #ID. just asking this question to know deep reason behind it.

Is it only a matter of W3C validation? or more than that

Answer 1

This post is just to add some more points to this interesting discussion ..

Its true that .. Id must have been unique and usage of 'duplicate IDs' must have been depreciated by browsers itself ..
But may be because these browsers want to make it more coder-friendly, don't seriously consider the "id" matter ..
So apart from javascript this mistake doesn't matter much to us too ...
(Depends on the version of the different browsers) Even CSS has no problem with it .. (apart from validation errors) check this out ..

But I assure that in-case of javascript usage it is prone to hell of bugs .. Once I had faced this problem .. where I had used same name for ID as well as NAME .. !

:-)