This is probably trivia for you, but I noticed some confusion at customer sites with this new feature of SCOM 2016:
If you try to import a Management Pack that is already imported, the "install" button of the import wizzard is greyed out and you cannot import the MP. This makes perfect sense, as it prevents the Management Server from processing a MP that it already has in its repository.
But, if you import multiple MPs at once (like for example the MPs that comes with an Update Rollup) it might not be that obvious. See the screenshot with the MPs of UR3:
From the screenshot above you can see, that the install button is greyed out. Reason for that is the Advisor Resource MP, that is already imported.
Unfortunately this is not easy and immediately visible in the wizzard, so you might have to select each an every MP to see, which one is already imported!
Once you removed the MP(s) that is (are) already imported, the install button is available and you can continue to import the other other MPs: