How to reproduce:
1. Open the “NetcodeRepro“ project
2. Open the “OutdoorScene“
3. Build and Run
4. In the Player click on the “Server“ button
5. Navigate back to the Editor
6. Enter the Play Mode
7. Open the “DontDestroyOnLoad > NetworkManager“ GameObject in the Inspector
8. Click on the “Start Client“ button in the Network Manager Component
9. Observe the Console window

Expected result: No warnings are thrown in the Console
Actual result: “Trying to spawn NetworkObjectId 2 that already exists!“ warning thrown in the Console

Reproducible with: 1.9.1 (2022.3.31f1, 6000.0.5f1), 2.0.0-exp.2 (6000.0.5f1)
Could not test with: 1.9.1 (2021.3.39f1) (Could not resolve the HDRP errors)

Reproducible on: macOS 13.5.2 (Intel), Windows 10 (User’s)
Not reproducible on: No other environments tested

Notes: The issue also reproduces when both client and server are opened from the Player