Excel Opening 2 Instances

I am using Office 365 (Excel 2016).

I have a shortcut on my taskbar to Excel.

When I right-click on the shortcut and select a file from the "recent" list, it opens the file, but it also opens a second, blank, instance of Excel, with no workbook, that is just titled "Excel".

The same happens if I open an Excel file in File Explorer by double-clicking on it.

However, if I click on the Excel link in my taskbar to open Excel, I am presented with a list of templates (on the right) and a list of "recent" files (on the left). Selecting the file in this way does NOT open a second instance of Excel.

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