That is not normal behavior for OneDrive. I use Quicken with OneDrive as you describe above. My instance does not change the file name. See the support article from Microsoft to resolve the issue.
https://support.microsoft.com/en-us/topic/duplicate-files-in-onedrive-fd47ce5e-8dd0-465e-9e3a-461e1a3cf613
@markus1957 I didn't know that OneDrive might mess up that way, but it might also be this:
When OneDirve adds your username to a given file it is a sign of a sync conflict. As in, the file got changed on two or machines at about the same time. You say you paused OneDrive on the machine while using Quicken. What was happening on the other machine? Also given depending on how big your Quicken data file is, and how slow your Internet connection is, it might take quite some time to finish the sync. You have to make sure that sync is completely done before opening Quicken on the other machine.
Off hand it sound like the second machine won't sync the file until something accesses it. I'm not sure why that would be, but that is what it sounds like.
After the file is opened for the first time on each machine a copy will download and stay resident locally on each machine for 30 days. From that point forward OneDrive will keep the cloud file copy and the machine copies in sync. You will be able pause OneDrive and use Quicken on either machine, but not both at the same time. Then Un-pause OneDrive to let it sync up.
One caveat. If the local copy on a machine is not used for 30 days, it will become what is called a cloud file only. Then you will have to open the file with OneDrive active for it to download the file to be stored locally. So if you haven't used Quicken for a month on the laptop, before you leave on a trip, open it on the laptop with OneDrive active to get a local copy downloaded. Then keep in mind if you use it on the road and you don't have access to the OneDrive cloud, the desktop copy will not be up to date until the laptop has access to OneDrive and syncs all the files you edited while on the road.
Also, be cognizant that syncing can take a several seconds, especially on the upload side. After closing Quicken and un-pausing sync, make sure you give it time to sync before opening it again.
Until very recently I was using Quicken with OneDrive active, but something in the R48 update is causing a crash during OSU so I have started pausing it again.
FWIW, I've been using Quicken several times a week on a laptop and desktop with OneDrive for a couple of years now. In that time, I can count on one hand how many times a duplicate machine named file was created on OneDrive and it was never caused by a credential cache issue. It was most always a Quicken software update initiating on open with OneDrive active which as @Chris_QPW indicated, does not always go well.