Hi Shmyrde,
The number of EDF files exported should be the same as the number of files you are trying to export. You seem to be saying that a single EEG file is exported in multiple EDF files, which should not be the case. Can you describe the file you are trying to export and provide a screenshot of the object in the Brainstorm database?
If it's a raw file, perhaps it is saved in multiple blocks which is why Brainstorm outputs multiple files, one per block. You can get around this by fully importing the raw file in the Brainstorm database (which should show up as a single non-raw data object), and then properly export it as a single file.
If it's a group of files/trials/blocks in the Brainstorm database, you can concatenate them first using our Standardize -> Concatenate time/signal processes before exporting it as a single file.
Cheers,
Martin