Installing craft with existing project config leads to duplicate default sites

Description

Installing a project on a clean database by running ./craft setup seems to always lead to a duplicate of the default site from the project config being created. It uses the same settings, but is created with a different ID / UUID, so you have to manually remove it and replace it with the default site from project config afterwards.

Steps to reproduce

1. Create a project on a local environment, creating a default site with project config enabled, assign some entries etc.
2. Add the project files, including project config, to some version control system
3. Install the project on another computer, pulling in the setup from the other environment
4. Craft is installed, but now a duplicate of the default site can be seen in the project config directory

Additional info

• Craft version: 3.6.14
• PHP version: 7.4
• Database driver & version: MySQL 8
• Plugins & versions: n/a

Start by reproducing the issue with ./craft setup on a clean MySQL 8 database using the existing project config and the steps above. Trace the installation path that creates sites and compare the created site with the project-config default; done means setup creates only the configured default site without a duplicate.