[Task Database Nightmare]

I have 1600 lines of data but each line is not unique to itself - it is a
list of agents with policy numbers. There are several hundred agents - but
not 1600 as many of the agents have multiple policy numbers assigned to them.
I am trying to create a letter addressed to the agent that list their
specific policy numbers. How do I do this without having the agent name
repeat itself for each policy number?