Version 2.5 of KPS for Windows introduced the concept of wallets so you can separate your cards in different files or allow multiple users to use the same application.
Wallets have the extension .SDF and are created using the wallet wizard. The actual wallet file is saved in the same folder as the application if possible and if not, it is saved in your “Documents” folder as is the case when the application is installed in the “Program Files” folder. This allows you to copy the KPS installation onto a USB stick and carry around the whole application which can then be run on any computer that has .Net Framework 4 installed.
The .DB files uploaded to Dropbox from the Android app are a separate entity. They are only used during either auto or manual import and export.
Exporting to Dropbox actually creates a .DB file using the data in your .SDF file and saves it in the “Auto Export” location. If you set this location to be the same location in Dropbox that Android uploads to, it allows 2 way transfer of the data between Windows and Android. The Import from Dropbox option replaces the data in your .SDF file with the data in the .DB file. It may sound complex but when you see it working it is actually very easy.
The latest (188.8.131.52) version of the Android app also allows multiple wallets so you can see and edit your wallets in both applications.