Maybe you just misspoke, But to clear up a possible misunderstanding: There are no files neither sheets nor audio in the database. The database is in the mobilesheets.db which stores the information where your files are and how they are used and displayed. You can choose to let MSP managing where it puts the files or maintain your own file and folder structure.
Having said this, you can in both cases reuse any sheet or audio file for other entries after the first import. You just have to use the local file browser in the audio edit tab and find where the audio file you want to reused is saved and select it. If you have the audio file already attached to your first sheet you can look in the audio tab for the path it is saved in.
(And you can manage your own structure in the Win version. I always do. But I'm not sure if you need to have the file location set for that in the initial install and if switching from one to the other is possible or easily done. Maybe you have to reinstall MSP for this.)
Having said this, you can in both cases reuse any sheet or audio file for other entries after the first import. You just have to use the local file browser in the audio edit tab and find where the audio file you want to reused is saved and select it. If you have the audio file already attached to your first sheet you can look in the audio tab for the path it is saved in.
(And you can manage your own structure in the Win version. I always do. But I'm not sure if you need to have the file location set for that in the initial install and if switching from one to the other is possible or easily done. Maybe you have to reinstall MSP for this.)