When you save a review to a local file the previous version is overwritten - unless you save it with a new name every time. However, when you check reviews into Archie, they are versioned, meaning that whenever you 'save' the review in Archie by checking it in, it is automatically saved as a new version.
Archie has several features related to review versions, but when you are using RevMan, it is quite simple:
Checking in a review will always create a new version. You can include a short description for each version.
When you check out a review, you will always get the most recent version.
A review version in Archie has a number of attributes that are not all shown in RevMan, but are listed in full here for information:
Version number – this keeps track of the order of versions. A higher number means a more recent version.
Version date – the date the version was created.
The version publication status - whether the version is a draft, has been marked or submitted for publication, or is published.
Version description – this can be used to describe what is unique about each version.
A person – the person who created a version is always recorded.