Is it possible to use an Xbox One and 360 controller at the same time in PC games?
I haven't tried it but I have both a 360 and an Xbox One pad.
They show up as two different controllers, so I don't see why it shouldn't work.
Here is what it looks like under Windows 7.
The answer is YES.
I've personally played games with multiple controllers connected, an XONE and an X360 to be exact.