Screen Percentage Not Supersampling In Sequencer

In 4.20 when i try and render from sequencer using the “Custom Render Passes” option and using a “r.screenpercentage” of 200, instead of super sampling, the editor just renders out the clip with a higher resolution

for example rendering at 1920x1080 with a 200 screen percentage would render as 3840x2160

This does not happen when using other render outputs like JPG, PNG, etc

(On the image below i have the option “Disable Screen Percentage” ticked, i did not have this enabled on my tests)

Hi,
Regarding the metallic and Roughness pass it make sense because the G-Buffer should be 200%.
However, I would expect the final image to be the same resolution as the screen.