According to the government if a student is availing one scholarship at a time, he is not eligible for any other scholarship offered by the government.
In any scholarship form, there is a field asking you that " Do you get any other government scholarship ?"
If you write NO then there is a possibility that you can get the other scholarship if you are not caught.
Many students availing PMSSS scholarship also get PMSS scholarship offered to students of Ex-servicemen. You can read more about PMSS from here.