DavidR
2
If the file was corrupt, I suspect that you wouldn’t be able to retrieve that information, e.g. a modified version of a digitally signed file would no longer be valid. I guess it would be the same for corruption as the file wouldn’t be the same.
So virus definitions update is a most likely reason, but an engine update could be another. Personally if you have two files that are the same I would always go with the latest version.
You may also see that some of the avast executable files are 9.0.2006.160 whilst others are 9.0.2006.159, this is currently the case in my 9.0.2006 installation. Notice I haven’t added the last element of the version number as that is the normal way of referring to the avast build number, any change in the third element .2006. or earlier elements would usually mean a program update would have taken place.