[Koha] Duplicate 300f (Physical Description) field

Hi, A few days ago I have reported a strange behaviour, where certain MARC fields would get duplicated. I have received one reply from Henri, asking if all the subfields were on the same tab. Well they were not - I split them between two tabs. 1. How can I fix it? Unfortunately the obvious solution of putting all these subfields on one tab makes the problem worse, as then all subfields of that field get duplicated - when I go to edit the biblio. 2. Should this be entered as a bug - if it's not already? Thanking in advance for any hints or suggestions. tomasz.