Sophos for Microsoft SharePoint: on-access scan is quarantining the same file many times

Issue
When a file is checked out, on-access scanning quarantines the same file many times. In addition, SharePoint is not substituting the removed text with the 'Replacement text', which is what usually happens when a document is found to contain disallowed text. 

Each time you try to download a file that has either been blocked or has been replaced/cleaned by on-access scanning, the file is scanned again.

The SharePoint 'Virus Found' window reports 'The file was cleaned and may now be opened on your computer.' This message loops: each time you click 'OK' to this message, SharePoint scans the file again and a new instance of the blocked file is placed in quarantine.The side effect is that if we have chosen to quarantine the item, then we quarantine the item multiple times.

What to do

There are two possible causes/solutions to this issue:

• This is a known issue: If the quarantined file has come from the 'Documents Center', and is a 'minor version' (i.e. not published), the workaround is to publish the document. If you do not want to publish it, it will continue to have multiple copies in quarantine.
• The other cause and the solution to this issue are described in the knowledgebase article Sophos for Microsoft Sharepoint: On-access scanning seems to scan files that are not being accessed (uploaded/downloaded) by users.