Reminded me of The Three Christs of Ypsilanti:

To study the basis for delusional belief systems, [psychologist] Rokeach brought together three men who each claimed to be Jesus Christ and confronted them with one another's conflicting claims, while encouraging them to interact personally as a support group. Rokeach also attempted to manipulate other aspects of their delusions by inventing messages from imaginary characters. He did not, as he had hoped, provoke any lessening of the patients' delusions, but did document a number of changes in their beliefs.

While initially the three patients quarreled over who was holier and reached the point of physical altercation, they eventually each explained away the other two as being mental patients in a hospital, or dead and being operated by machines.