Actually, after seeing the rest of the replies I've realised that this is something that I had to deal with myself a while back.

The way I got around it was (as has been suggested) to assign individual names to each INPUT control. In my case, I was using arrow images as sorting buttons. The code to render the HTML was a little like so:

print qq(<input type="image" name="sort:$field:asc" src="$image_dir/do
+wn.png">);
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The above was within a for loop, where the value of $field was changed on each iteration, to produce a unique name for each "button".

I had about 20 of these little "sorting" buttons on my page, so when it came to working out which one had been clicked (if any), I did this:

my ($sort_string) = grep { $_ =~ /^sort/ } @params;
my ($sort_field, $sort_dir)
    = defined($sort_string)
    ? $sort_string =~ /^sort:(\w+):(\w+)/
    : qw(avin desc);
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The above worked fine in both IE and Firefox.

Hope this helps,
Darren :)