I'm not sure we're talking about the same thing? It doesn't matter whether or not I press the Command key here when clicking a notification banner on my desktop Mac, for Invision Community, it always rewrites one of my website's already opened tab and never opens a new tab.
I'm talking about clicking this:
Here's a simple example:
I have only one tab opened with page A on my website.
I click a notification banner about a new reply to another topic.
The new topic overwrites the tab that had page A opened. There's no way to go back: the back button in Chrome is disabled (as if I was never on another page before). The tab does not register the overwriting as a new page in the history, it's the same page, only its content was overwritten. I can't go back to page A.