Blood Hunter: If my marked target deals damage to multiple people standing within 5ft of me, does he take the psychic damage more than once?

quick question about blood hunter, specifically the 6th level ability. If my marked target deals damage to multiple people standing within 5ft of me, such as with burning hands, does he take the psychic damage more than once? Just once.

— Matthew Mercer (@matthewmercer) January 29, 2020