It wasn't specified. The split was caused by some exotic flowers getting mixed in the matter streams causing the two crewmen to bond. During the episode we saw the Doctor experimenting with the flowers and other biomatter making hybrids and then making unfortunate messes whenever he tried to separate his hybrids. Just imagine this stuff weaponized. A boarding crew of 80 armed bastards beams over only to discover that upon materialization, they had become one really confused bloke. Would their 80 guns and uniforms and underwear combine like Tuvix and Neelix's clothes combined? In Deadlock, did they say that a boarding party of 400 Vidians could beam over or did beam over?