Wisely We would welcome a feedback ticket under the "Search Quality" tag if you would like to report it.
I can talk briefly about it:
It is hard to say that it is a "bug" than just a generally quality improvement idea; many other search engines will return both versions of a site like that sometimes - and it is a quality that we inherit by using 3rd party indexes.
Generally speaking - deduplicating mobile results on our end is tricky. There are no standards when it comes to this, only conventions that sites tend to follow, others do not - some use domains, others use paths, others use URL parameters - and indexes we use don't just tell us what it is, as nice as that would be 😃
So currently, it is safer for us to leave the extra result than be wrong. But, thankfully we give you tools (domain blocking) to quickly push it out of the way yourself.
Anyways - Yes, please open another ticket, and as it receives upvotes we can work towards prioritizing some kind of improvement. Perhaps a few rules for the most popular sites / examples where this occurs could be enough, I'm not sure.
