Nothing to do with the installation process. They just share the same list of settings. I believe that this list contains items other than the Advanced watchlist, but can't remember if hand what these are.
Sent from my iPhone
Like Doug said; this has been the case since FM12. The watch list is stored in a plist that is shared across the versions. If you crash hard you'll lose it all. Both the watch list and your fav hosts list. You can save it out and restore it with a bit of OS-level scripting
Thanks much. Not sure why, but at one time I thought each version had it's own plist file. This can be helpful.