What happens if you Ctrl+C, Ctrl+V on the Doctor’s data files? Do you duplicate a sentient being?
In “Virtuoso”, Tom & Harry try to reproduce the Doctor but they’re basically trying to make him from scratch, so I don’t think their failure is relevant.
At the end of “Author, Author” we see many repurposed EMH Mk1s working as miners:
…and they seem to be self-aware, so I guess we have to assume that it’s technically feasible.
But then what happens if you Ctrl+Z?
they gave the convoluted explanation that emh doctor was more advanced than the ones in the mines and its hard to replicate his hologram programming.