This has definitely been a problem for a long time. I see it frequently. For instance, every year about this time I go to download all my past year’s bank statements to go through for my tax preparation. At least one of my banks names the downloaded file “stmt.txt” with no indication of which month it is. If I click on several months to download each statement, I will only end up with the most recent one as the others get downloaded and then overwritten. So instead of clicking 12 times (once for each month) I have to click, go to the Downloads folder, rename the file with the appropriate month number, go back to Safari, and click on the next month. It’s annoying.
I’ve had to do this for years, though one of my banks this year did finally change their filenames this year so now it only happens with one bank.
That’s just one example: I’ve had the problem with downloads on other sites, too. (Like a clipart/stock photo site where I painstakingly went through to find and download thumbnails of a dozen possible graphics I might want to use, and when I went to the Finder there was only a single file saved, called preview.jpg – the site named all the thumbnails the same. 
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