Both Compact and Local DB are Database Engines. They are different, and you do not need (nor want) both. Do not install Compact SQL; it is deprecated and not recommended.
Uninstall SambaPOS.
Uninstall Compact SQL.
Look in your User Documents folder for the SambaPOS folder. If there is a SambaPOS SDF file in there, delete it (this is a Compact DB). In fact, delete everything in the SambaPOS folder.