Following up on this thread, which was locked:
Currently, this behaves correctly if you start a reply using the quote button, but the issue still occurs if you have an existing reply and use the quote button to add text to it. If the quote contains a link, and the other conditions for the warning are met (quoted post sent within the last two weeks), you’ll see the duplicate-link warning.
Quoting the warning message so someone searching for it can find this thread:
It looks like your link to [domain] was already posted in the topic by [user] in a reply on [date] – are you sure you want to post it again?