the reason JAWS is speaking some strings twice is as follows: 

JAWS uses some framework to gather information like the page title.Since a few years there's a new framework called UIA. JAWS hooks itself in the UIA framework and gets the information there. But the old one still exists and this is reason some things are spoken twice. And because UIA has a lot of information (at least in Microsoft Edge) JAWS is quite chatty there. 

As far as I know there's a setting to disable the new UIA methods. Since I haven't an English version of JAWS I can't remember the exact name. I think it was something like "UIA" or "Automation". But if you disable the checkbox JAWS doesn't announce the UIA messages like the one if a download was completed. 

To proof if I'm right with my suspicion you can use Firefox, since Firefox doesn't use UIA. Edge is the browser which uses UIA most followed by the browser which use Chromium as a base (Google Chrome, Brave and so on). 

Hope this helps

Udo