Hi,
version 7.0.116 (not sure if this happens in previous versions)
After a plugin imported from XML, if you do not save before you import the second XML file, system setting fields from first plugin will stay and merged into the 2nd plugin
Steps to reproduce
1. import plugin with system settings
2. import another plugin without system settings
3. save plugin
you will not be able to import and save the first plug again because duplicated system setting key.