We appreciate that you are trying to help, but you have got it totally wrong, the system is not infected, you have to exercise more care when offering advice.
The System files section of the chest is where avast stores copies of important system files, they are not infected.
There are three sections:
The only area you should be interested in is the Infected Files section, this is where the files detected by avast and selected by you to move to the chest are placed.- The User Files section is where the user can add files they suspect of being malware but not detected by avast.- The System Files section is where avast keeps back-up copies of important system files in case the original becomes infected (leave them alone).- The All Chest Files is a collation of the three sections.
So you have nothing to do. As far as duplicates go, when one of the files gets updates (possible windows updates), then avast would move a copy of the changed file to the system files section of the ‘Chest.’