Comment 18 for bug 1864810

I was really curious what the root cause really was and so I set on a journey to discover it.
The result is: https://github.com/yoctozepto/ansible-experiments/commit/e2dc35c3c55a61906aa6f95761d5e7d68ae556bd

TL;DR including/importing role with handlers along with setting vars will create
separate handler instances if there was any include along the path to role
with handler.

So the 'duplicate name' also was a false reason. Good to know I think.