Steps to reproduce
* Install a site using a profile in English
* Enable locale, language
* Add a second language e.g. Swedish
* Set default language to Swedish
* Export configuration
* Install site again using same profile
* Config import configuration
* You will see (or at least I did):
Synchronized configuration: update ...
Finalizing configuration synchronization. [ok]
The import failed due for the following reasons:
Unexpected error during import with operation create for shortcut.set.default: SQLSTATE[23000]: Integrity constraint
violation: 1062 Duplicate entry 'sv-5' for key 'PRIMARY': INSERT INTO {locales_target} (lid,
language, translation, customized) VALUES (:db_insert_placeholder_0, :db_insert_placeholder_1,
:db_insert_placeholder_2, :db_insert_placeholder_3); Array
...