Request #50897 has been Rejected by dbermond [1]:
The opencv2 package was refactored to not conflict with repository
opencv. The package now provides the right non-conflicting files in
/usr while also installs to /opt.
[1] https://aur.archlinux.org/account/dbermond/
MarsSeed [1] filed a request to merge opencv2 [2] into opencv2-opt
[3]:
opencv2-opt is a better, non-conflicting package for the same.
[1] https://aur.archlinux.org/account/MarsSeed/
[2] https://aur.archlinux.org/pkgbase/opencv2/
[3] https://aur.archlinux.org/pkgbase/opencv2-opt/