Openvix operates in this way for several items, none of which are crucial.
There is a "system" file in one location.
There is a "user" file in another location.
It checks for the user location first. If not there, it uses the system one. What this means is that when the sytem file is updated, it wont affect the user one. If a user has put a certain file there, why should it be removed and overwritten? It is undoing what the user actively chose to use.
If you want to use your own bootlogo/backdrop/background (they end in .mvi) put them in /etc/enigma2/