[Koha] why do i get a Duplicate Record suspected message while adding records while there is no similariyty between the books in content or name or author or copy number

[Paul]

At 02:36 AM 3/12/2013 -0700, tanzeem wrote:
>Hi
>I get a Duplicate Record suspected message
>  while adding records while there is no similarity between the books in
>content or name or author or copy number
>or DDC no or keywords,or publisher or keywords.
>When i was adding the record for Dermatology and sexually transmitted
>Diseases book
>I get the message
>Is this a duplicate of Adolescent medicine today?
>
>How does this show up?Any idea anyone.
>I know that i may be able to skip this by clicking the button >No, Save as
>New Record
>
>But i want to know why Koha shows this message

You don't say which version of Koha you are using, but do you by any chance 
have duplicate Control Numbers (Marc 001)? You can verify this by running a 
"report":

SELECT GROUP_CONCAT(biblionumber SEPARATOR ', ') AS biblionumbers,
EXTRACTVALUE(marcxml,'//controlfield[@tag="001"]') AS id FROM biblioitems
GROUP BY id  HAVING count(id) > 1;

Best - Paul