Differences between single render and queued render?

[guillaume_lw]

Hi,

I am getting different results when I render my scene manually (i.e. click the render button) and when I render the same scene with the exact same settings via the render queue.

Steps to reproduce:
1. Open render window and click render.
2. Immediately after first render is complete, open render window again, go to queue tab, click "add job".
3. Click process queue.
4. The two renders look different (see attached screenshots).

Attachment 1 is the manual render.
Attachment 2 is the queued render (in which some areas are noticeably darker).

Render options are set to a maximum time of 1 minute. These options were set before the first render was created.
The object I'm rendering is the only object in the scene, and has a "plastic" material (see attachment 3 and 4 for material settings).

Other info:
Windows 10
Keyshot Pro v 6.3.23

Any help would be much appreciated, thanks.