If a module has been installed and the module files were deleted, the parameters would still exist in the database. If the module files were copied again to the modules directory, installing the module would introduce duplicate module parameters, so when installing a module, check if it has been installed previously and call its remove() function before installing the module again.
Merge pull request #1 from haraldpdl/missing_order_total

If a module has been installed and the module files were deleted, the pa...