How to reproduce:
1. Open the attached project "1225811 - 2020.2.zip"
2. Open the "SampleScene" Scene
3. Select "Cube (with Timeline)" GameObject in Hierarchy window
4. Select RecorderClip in Timeline window
5. Enter Play Mode
6. Wait till RecorderClip finishes and exit the Play Mode
7. Open folder "1225811 - 2020.2\recorders" in File Explorer and go trough rendered images

Expected result: the images from both cameras are not flipped
Actual result: the images from one of the camera are flipped vertically

Reproducible with: Recorder preview.1 - 2.1.0, preview.1 - 2.0.3 (2018.4.18f1), Recorder preview.1 - 2.1.0, preview.1 - 2.0.3 (2019.2.21f1), Recorder preview.1 - 2.1.0, preview.1 - 2.0.3 (2019.3.5f1), 2020.1.0b1, Recorder preview.1 - 2.1.0, preview.1 - 2.0.3 (2020.2.0a3)
Could not test with: 2017.4 (errors in console after downgrading)