duplicate ID

[Joerg Schaber]

Hi,

creating a ncbi database using dbiflat I always get a few times the message
"Warning: Duplicate ID skipped: '<null>' All hits will point to first ID 
found".
Even though it does not seem to have severe efects I would like to know 
what duplicate IDs are ment.
I checked the genomes IDs and acnums and they seem to be OK (all *gbk 
files downloaded from NCBI) and they all have entries and are not 'null'.
Any idea what's the problem?
here the command I use:

dbiflat -idformat gb -directory "." -filename "*.gbk" -dbname "ncbibac" 
-release "1.0" -date "26/11/02" -fields acnum,des,taxon

greeetings,

joerg