I will start by saying that I do not know what change caused the following to occur, since both QHY and SGP have undergone updates since the original behavior was noticed.
At the beginning of this year I noticed that if I selected 2x2 binning in SGP sequencer or focus/frame, the 2x2 binning flag would be set in the QHYs ASCOM settings panel.
This week, I started to image with 2x2 binning in SGP - but I later found out that the QHY ASCOM settings were on 1x1. I only discovered this when I came to do flats and darks, and I set 2x2 binning in the camera properties and 2x2 in the sequencer. The result was a file that was equivalent to 4x4 binning. Thankfully I noticed before I dismantled the rig.
It seems that the binning in SGP does not affect the settings in the ASCOM settings, so the two binnings combine! That’s a lot of files for the bin.