Make sure you click on Name, not Ext when sorting the panel.
i have a folder with many typo3 versions to switch between the instances fast and have multiple linked typo3 pages.
if i open the folder with this versions in winscp, the sort is very strange. So it's hard to found the version i'm looking for.
look at this screenshot:
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in the shell, this looks like this:
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the 4.5.1x versions are not sorted correctly but the 4.2.x and 4.6.x versions are.
I'm running Windows 7 SP1 Professional and WinSCP 4.3.6 (latest stable)