"User XYZ already logged in to this database" message, when have two separate EXCEL.EXE sessions (one originating from main Controller client, the other opened outside of Controller)

Symptom

Example:

Imagine the following scenario:

1. Ensure that all sessions of Excel are closed (no EXCEL.EXE processes inside Task Manager)

2. Inside the 'main' Controller client (CCR.exe), click 'Company - Data Entry - Reported values' and open a data entry form:

This data form is a spreadsheet in Excel, so if you look in Task Manager now you will see one EXCEL.EXE process:

3. Next, the user launches Windows Explorer, and browses to a folder where they store their Excel reports (XLSX files)

4. User double-clicks on an XLSX file. This opens in a new session of Excel.

You can see that this is true because:

(a) The Excel splash screen appears shortly after double-clicking the file:

(b) Inside Task Manager there is now a second EXCEL.EXE session:

5. Inside the new Excel session (where the XLSX file has loaded), user clicks on the 'Controller' add-in menu item.

- The user sees that they are not logged on to Controller, because the 'Log on' item is active/visible:

6. If the user clicks 'Log on...' (and types in their username/password) then the following message appears:

User XYZ already logged in to this database