Yes and thanks.
I also just found the solution on my side, and I was going to post to indicate the solution.
Do you have an imposition node set to 2-sided in the workflow. I think the settings here will overide other settings.
All jobs witch are submited with FFC panel are always in 2 sides on printer FFPS.
Default setting on FFPS files are 1 side, printer node on FFC are 1 side, and I try submiting with overwriting job ticket option, but the result is 2 sides arriving on FFPS file.
I think it's a bug ?