@Mixx - it isn't possible to use the two plugins together in that way. They are both making use of the same feature in calibre, and the way it is being used means that their usage is exclusive of each other - i.e. books are either specially makred as duplicates, or they are specially marked in a temporary list. They cannot be both. In the same way you could not mix Quality Check results with these plugins.
Perhaps if you described why you want to use Temp Marker on those results of Find Duplicates we could make another suggestion.