The first victim was subjected to an unprovoked attack inside the Acapulco Nightclub at around 2am on Saturday, September 4.
The second victim, a witness to the first incident, was then attacked as well.
Police today released details of both incidents as they appealed for witnesses.
The suspect is described as a muscular, white man in his mid 30s. He was between 5ft 11in to 6ft 2in and had blonde or brown hair.
He was wearing a white shirt and dark trousers, and spoke with a Yorkshire accent.
Anyone who witnessed the assault or has any information is asked to contact PC 5642 Alex Langley at Halifax Neighbourhood Police Team via 101.