Need to suppress repeating values in parameter drop-down list

I'm using a Report Parameter within a SQL Reporting Services Report, and the appropriate values are populating the parameter drop-down list. However, one of my tables has several records with the Service Provider ID. My question is how can repeating values be suppressed in the parameter drop-down list. See below for example. Any insight/advice is appreciated!
Service Provider ID 21
50
60
60
60

you can do a SELECT DISTINCT in your query to get unique records.