Could both of V2 and V3 are installed and existing on the same PC or Mac, and user can choose to use V2 or V3 without additional settings every time when he/she brings V2 or V3 up? Thanks.
Yes it is possible.
Note that they use different User data folders.
It is possible but I personally don’t advise doing it on a Mac. The Mac application will overwrite the existing installation.
On PC it is not an issue, just on Mac.