Forcing record creation after duplicate warning

[knirirr]

The current way of doing this is:

1. Fill in details for new record.
2. Click submit button.
3. Inspect list of potential duplicates to check that this isn't really a duplicate. If not, then...
4. Click "I know what I'm doing".
5. Click submit button again.

Step 4 confuses some users, who appear to think that clicking it should submit the record immediately. Perhaps we should do that, or offer a more obvious indication of the need to resubmit?