Source files can usually be read by any number of processes at the same time if no other process is rewriting those same files (and no-one has an Exclusive Lock on these files). As soon as someone starts saving that QVW (for example during/after a reload) you will not be able to make a copy.
Windows backup programs solve that situation (for example, database systems keep their files open 24hrs a day - so how do you make a backup then?) by instantiating the file system (using the VSS sub-system) into an previous copy and a current copy of files. It acts like a sort of "freeze" of a particular state of files. The previous copy can be read while the current copy is rewritten.
IMHO you cannot use that same technique in a batch file. You'll probably have to wait until everyone stops writing the QVW documents you want to copy.