A thought....
If you are installing both V4.1 and V4.2 because you intend to use both of them at different times, my gut feeling would be to put them in separate Runtimes, just to make sure they are completely independent of each other. That is what I did, but not based on any particular reason, just to be tidy and safe.
Izi

"If I were a shadow, I know I wouldn't like to be half of what I should be."
Mr Otsuka, the old black tomcat in Kafka on the Shore (Haruki Murakami)