Hard to tell that a bug is a duplicate.

[Jani Monoses]

It is not immediately obvious that a bug page is of a duplicate. The sidebar text is not enough. I spent a while looking at a New bug, following whether it is known in Debian just to find another LP bug that it is a duplicate of. So I found this out in a roundabout way not because LP made it very obvious.
I could not reopen this or I would have.
https://bugs.launchpad.net/launchpad/+bug/136510

I think a much more obvious way of marking it duplicate would be to have the whole page visually different, much more of the background grayed out, no controls working, a large pointer to the master bug where people are encouraged (and only there allowed) to discuss and change it's status.

Or at the least mark it Fix Released (dup) or something so it does not look new. It cannot be expected that for each bug one sees, one first checks the sidebar to see if it is a dupe. And there should be an obvious way to mark it as not actually dupe in case it was marked by mistake.

[Robert Collins (lifeless)]

The status table on duplicate bugs is also greyed out and the controls cannot be used. This is one of the rectifications you suggested, so I'm not clear why you consider this open. (Or had you not noticed that?)

[William Grant (wgrant)]

Nowhere on the page explains why the bug is a duplicate, unless you think to look right down the bottom or carefully read a very subtle line in the middle of the sidebar. The widgets appear to be disabled for no reason at all.

[William Grant (wgrant)]

s/why/that/

[Curtis Hovey (sinzui)]

I agree with William that the bug is not really fixed. The duplicate bug issue is similar to "this bug was converted to a question", which has it's own own open bug.

The page needs to state the special condition before the affects table. We want a prominent way of presenting this that does not wrongly highjack the notification style.