"Extra" file just appeared

This is likely a dumb question, but I want to be sure I’m not screwing something up if I delete a file.

This afternoon an “extra” file showed up alongside my Sparkle website file. The extra file carries the name of my site file, followed by sparkle.sb-9d1df48a-YBeKxq. I’m assuming this is some sort of temp file that should have disappeared when I closed Sparkle. I’ve been using Sparkle since late last year and this is the first time I’ve seen a file like this. The file is about one-fifth the size of my site file.

Is it safe to delete this file?

I’ve heard of that in the context of folder sharing (for example this thread about office 365), they definitely are not produced by Sparkle.

Odd. I don’t use Office. I deleted the file and my site file still loaded. That’s good. I made a change in the site file, saved it and watched the folder as it was saving. Another file with a similar name showed up for a few seconds, then disappeared. But when I quit Sparkle, another long-named file appeared and stayed. Guess I’ll just keep deleting them.

It’s not about Office. It’s about some form of sharing.

OK. Interesting. And bizarre. I haven’t changed settings or installed anything new. Just really odd.