It might be that the strange reference is getting added when saving to the SharePoint list. Here's what I suggest:
1. Do the steps you describe for day 1.
2. Open the form in Notepad and search its contents for xdado:OsoZ9.
3. Do the steps you describe for day 2.
4. Download the form from the ShP list and open it in Notepad. Search its contents for xdado:OsoZ9.
I know this won't solve the problem but at least it narrows down the source of the issue.