Only one version of A+ at a time?

Hi, my first post here so sorry if this has been done, I’ve looked but couldn’t find an answer.

The latest versions say only one version can be used at a time, I’ve been happily using A+ since 1.5.?? and have kept many versions in a separate file on the hard drive which stores my music. I am reluctant to download the latest version if to means I can’t go back and compare to earlier incarnations. Could this be a problem or am I being over cautious?