Creating copy of phone (apps, settings etc.) I have two rooted Huawei P9 Plus phones running Android 7. Now I would like to copy the apps, the settings of the apps, the system settings etc. from one phone to the other phone so that both phones are exactly the same.

How can this be easily done? I have root, so I could also use an app requiring root.
It can be done using many ways,


if you use the same Google account on both devices then just a simple cloud restore from the initial setup screen would setup everything just the same. (when I was switching roms frequently which are all based upon lineage, or same feature sets, I noticed even personal settings appeared to be restored along with all apps, messages and other data) So I think It'd be the easiest.
Mentioning root You could also use apps like titanium backup etc (btw I faced lot of after restore stuff like setting up permissions for each app and its just for the apps) also do note that new apps for doing the same are also available.
Assuming you are rooted on both of your devices with a working twrp recovery(as with most cases) and every config of both phones being the same then you can do a nandroid backup (backup from twrp menu) to your sd card transfer the backup folder to your other phone and then restore it there.
ps. 
(tl;dr I don't recommend this to you by any means but It can work taking your case.) 
I haven't tried it on two phones and would have a high chance of breaking your phone if things doesn't match well (nandroid backups can break even on cases where the new roms doesn't match older ones)