Probably not, but it’s part of the Copy to clipboard
If you review your Manager screenshot, it has six columns - A to F
The spreadsheet is only displaying the source data - A to E, not any calculated data.
The sixth column (F) is a running total, which is a calculation by Manager.
That calculation process is not exported.
@Indinfer, the explanation is that the function copies in TSV format. Each cell in the display is followed by a tab. The spreadsheet interprets the tab as an instruction to move to another cell (which happens to be blank), so you end up with an extra column.
You can see this in action by pasting into a text editor instead of a spreadsheet. The behavior is common to all lists in Manager.
You can also see the converse of this by repeating your experiment with a report instead of a list. While reports are also copied in TSV format, they are more extensively defined in the program and do not include those tabs after the final cells in a row. So you do not end up with the extra column.
Yes, I see @Tut is right. Having the final column being followed by a tab causes the extra column. @Brucanna 's explanation might be how this could happen. I think it is good that the running total is not included in the copy to the clipboard.
While it is true calculations are not exported, that has nothing to do with the behavior you see. In your example of bank balances, the running balance column showing the result of calculations just happens to be the farthest right. So you might think the blank column in the spreadsheet has something to do with that. But it does not. Look, for example, at Fixed Assets or Sales Quotes (or any other tab where the totals are at the bottom). The calculated totals are not exported, but the extra column still exists because of the tabs, and it is still on the right. And the calculations that appeared on the bottom of Manager’s list do not cause an extra row to appear on the spreadsheet.