As best as I can tell, you CAN NOT exceed the voltage rating of the capacitor. Your dealing with capacitors not resistors.Now it will surely have an effect on the capacitance. Take the formulas for determining resistance in series/parallel and reverse them for capacitance.
Yes the voltage capacity will double and the capacitance value will be half that of the single cap for same value caps. You need to put a 100K resistor across each to make sure the D.C. voltage
divides equally across each cap. This has been done on tube amp power supplies for decades. Skippy, anything to add?
Nope, and I learned something new. That's what I like about this forumn. Speaking of tube amps, I'm about to build my very first one and looking forward to "regressing" as some SS guys would say. I also just bought an old Thorens turntable. Hey if your going to regress you might as well go all the way.
P.S. Harry you sound like an engineer/troublemaker. Welcome to the board.