I have a question it is sometimes possible to use both the release version and the beta?
Yes. They install in different places but use the same configuration files (unless you set them up differently). A little more information here.
Okay how can you do that and also with different packages
The same set of packages will be used for both Atom versions because they’re stored at the same location:
~/.atom by default. However, you may be able to get around that by specifying a different
ATOM_HOME location before starting the stable and beta version.
For the moment, I do not manage to install the two for mac