Good catch this is in fact a real bug. 

Before I propose a fix I'd like to clarify if this is something that can happen from the API point of view.
Devlin:  Is upgrading a notification from simple to progress supposed to be possible? Are downgrades also possible then?

Not sure if related, but I noticed that there are two entries for Chrome in the Notifications system preferences. 

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> Is upgrading a notification from simple to progress supposed to be possible? Are downgrades also possible then?

Yes.

> Not sure if related, but I noticed that there are two entries for Chrome in the Notifications system preferences.

Correct, because we display different kinds of notifications (both banners and alerts) whereas the system only allows an individual entry to display either.

lgrey@ (currently OOO) - can you take a look at this one as well?

Hello, I am experiencing the second issue, duplicate entries for Chrome in Mac System Preferences / Notifications settings.  MacBook Air, macOS Sierra 10.12.6, Google Chrome Version 60.0.3112.90 (Official Build) (64-bit).

FYI, I had duplicate entries for iTunes in notifications preferences as well.  By executing the following in Terminal I was able to eliminate iTunes, but Chrome is still duplicated.

cd $(getconf DARWIN_USER_DIR)com.apple.notificationcenter/db
move db db.temp

john@e9data.com, per comment 5, the multiple entries in System Preferences should be intentional. Are you getting duplicate notifications as well?

rdevlin.cronin@, what do you think re: the question in comment 2?

fwiw I already answered that in #c3 -- yes, these are possible.

Notifications sharing an ID should replace each other. The problem is that by having separate listings for banners and alerts, they effectively have different "queues". Moving a notification from one to the other will thus result in it showing twice.

One solution might be to issue an explicit close on the other type? I.e. a banner with id "foobar" is being shown, we show it, and then try to close an alert with id "foobar". It's a hack and doesn't give us clean replacement, but we're not going to be able to get that anyway..

Look at the app "ChronoSync" in the Notification list. They also have two entries. The subtle differences in the app icon and the title of the notification entries helps distinguish which entry is which and what their purpose is. (see attached).

In case of Chrome, the issue is really not that there are two entries. They issue is that they have the same icons and titles, therefore it appears to the user as if it were a bug. And so it results in endless amount of threads floating around about it. If the entries were clearly labeled and possibly had subtle differences in the icon, people would not mistaken it as a result of a possible "issue". And so, developers would not have to waste their time creating bug reports and answering them.

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That's not exactly the same thing. I don't have that application installed, but I would guess that ChronoSync Scheduler is a helper binary, hence the different name and icon. Both entries display banners and not alerts.

This is silly. Which of the two entries in Notifications is supposed to be displaying Alerts, and which one is supposed to be displaying Banners? And why does this situation even exist?

I ask because I've changed settings under both entries.

These two entries at LEAST need unique names.

Perhaps the second set of Notifications can be spun off to be handled by a do-little binary with a distinct name, which then communicates the desired Notification settings to Chrome?

***UI Mass triage***

Adding labels for expert review.

Able to reproduce the issue on Mac OS X 10.13 using Canary #72.0.3617.0