Back when I had my old 2014 Prius, my smart key would not work when it was close to a smartphone. I recently traded in my 2014 Prius when I bought my new Prius Prime. With the smart key for my Prius Prime I noticed it doesn't have that problem. That is mostly a good thing, but it can be a bad thing if you want to prevent car theft.
In my 2012, I carry them both in the same pocket. Once in a while, I have to shift the fob for the car to recognize it
