Two installations of Qt on OSX? My setup (OSX 10.13.6) appears to have two installations of Qt5: one in /Library/Frameworks (/Library/Frameworks/QtCore.framework, /Library/Frameworks/QtGui.framework, etc.), but I also have one installed by brew at /usr/local/Cellar/qt/5.13.0. Is it a good idea to have Qt at two locations? Is it a good idea to remove the one at /Library/Frameworks and keep the one brew installed?
Often had two versions of a particular app installed (usually in the standard apps location). 

Did this with Excel - never had an issue. Also with Qt at one time.

I just made sure the newest one was the most recent install for any libraries necessary.