Let's assume that computer programs can reach a level of consciousness indistinguishable from human consciousness.
Then, clearly, computers could run multiple consciousnesses.
Those consciousnesses would receive all of their "sensory" inputs from their programming.
The number of consciousnesses that could be run at any one time would be purely a function of computing power.
Any civilization that could do this would do this.
Any civilization that could do this would be able to run social science experiments, in which the computer consciousnesses would be subject to various beginning states, requiring multiple massive multi-consciousness programs.
Necessarily, the software consciousnesses in such an experiment would not know that they are software.
With each instance of a massive multi-consciousness program, the ex ante likelihood that any given consciousness is "real" rather than software decreases arithmetically.