I noticed (recently, I think) that some of my daily notes are split in two. One of them is named
<date> and the other is
I use Obsidian on two devices and synchronize the data on the fly (with Syncthing) so this may be an indication.
I did not manage to replicate the behaviour on request so knowing when Obsidian creates such a file would help a lot to track it down.
I’ve seen the same behaviour of you try to create a second “Untitled” note, so I reckon you’ve got a template trying to create the file again, when it’s already existing, and therefore it does the second best thing and creates a file with the " 1" appended.
The fix is to locate where you’re creating these files, and change the logic so it’s doesn’t try to create it when it already exists.