XLS padlock opens 2 instances in excel 2013

I did just get the info from a new client that is using excel 2013 that instead of 1 instance, 2 instances are opened of the workbook. However one instance seems to be empty and the other one does have the workbook. The strange thing on top of that is that the “empty” instance can however show a print preview. When closing down the “empty” instance it does however request to save the file. If clicking cancel then the only way to exit seems to kill excel. Any ideas what is happening that I could tell my client ?

Which version of XLS Padlock are you using?

2.2.1 the latest one

Could you ask your customer if his Excel is configured to open other workbooks or templates at startup?
For instance, in this folder:
C:\Users\user name\AppData\Local\Microsoft\Excel\XLStart
And follow instructions from:

=> Stop a specific workbook from opening when you start Excel