When first starting Krita, instinctually double clicking a recent file will open 2 copies of that file. This behavior isn't seen nearly anywhere else in Windows as far as I'm aware, and if Krita wanted to fit more in place with user's natural muscle memory for opening files, it would be better to have one click select, and a second click shortly after to open. However that would interfere with user's muscle memory if they had already gotten used to the single click. As a compromise, it may be better to have a single click open the file, and any subsequent clicks be entirely ignored to prevent duplication. While it doesn't necessarily hurt in any way besides being a minor annoyance, 'fixing' it this way wouldn't change anyone's workflow or make anyone complain, so I see no reason not to. I am unsure if this behavior happens on other OS' builds.
It was a case in Krita 4.2.9, but Krita 4.3.0 works as expected. Can you please check if you're for sure using the latest version? And you haven't say your system either.
My bad, this is on a Windows 10 N system using 4.3.1-alpha (08ecea2) On trying to recreate it, I think I might be mistaking a different functionality. All I know is when I would first open Krita and accidentally double click my recent file, it would open twice. Now that I try this again, it works as expected and only opens once. If I had to guess what actually happening, I probably turned off my desktop with the file still open. And upon starting up my computer again and opening Krita, it then loads what I had open the previous day. but during the time that it's loading that, it allows me to click the recent file, thus opening it twice.
This report led me to finding a related trick: If you click multiple different recent files in quick succession, you can open multiple files at once. Likely unintended, but likely not worth fixing either.
Confirming, with following steps to reproduce: - open some big file that will be opening for several seconds (to make it easier later) - close it - click on the file, then click again (you can do double-click and then double-click or replace any of them with single clicks, it doesn't matter, what matters is that you trigger opening it twice) - wait - see that it opened two documents @tom shows that it could be used for good but... I think there should be some blocking; especially when opening big images, since there is no progress bar, it can look like Krita is idle and impatient user can click it again and again, resulting in a RAM disaster. But it does look minor now when the double-click is fixed.
Welcome Screen now is disabled after first clicking, so you can't open two files.