Hm. I’m wondering about this. What’s your DT sync conflict setting? I used to get tonnes of copies with a similar workflow, albeit not in Obsidian (I think I was using iA Writer at the time).
Find it here, in preferences:
FWIW, if you are on “Duplicate documents,” switching to “Use latest document” resolved the (possibly different) problem for me and hasn’t caused any issues. (Good backup practices are always valuable though!)