It can happen, that a keyword is ranking twice for the same URL on different positions. This means one URL can land on position 20 and 21 with the same keyword. This does not imply keyword cannibalization, as a keyword ranking twice for different URLs would. This phenomenon is not caused by a bug in the Searchmetrics Suite, but is due to the way Google works.
When a keyword is ranking on the last position of a result page, sometimes it is also ranking on the first position of the consecutive one. Google is responsible for this behavior, because it is using different data-centres for each data request. Same applies for regular user requests, however normally the user won't notice it.
Because Searchmetrics is displaying the crawled google data exactly as it was found, the keyword ranking twice for the same URL will also show up in the Suite.