CREATE PROCEDURE ...
@NameList Varchar(8000)

Select * from People
where (FirstName+'-'+LastName) in dbo.Split(@NameList,',')
....

CREATE FUNCTION [dbo].[Split]
(
    @Input VARCHAR(8000),
    @Delimiter CHAR(1)
)
RETURNS TABLE
AS
RETURN
(
    WITH Split(stpos,endpos)
    AS(
        SELECT 0 AS stpos, CHARINDEX(@Delimiter,@Input) AS endpos
        UNION ALL
        SELECT endpos+1, CHARINDEX(@Delimiter,@Input,endpos+1)
            FROM Split
            WHERE endpos > 0
    )
    SELECT  SUBSTRING(@Input,stpos,COALESCE(NULLIF(endpos,0),LEN(@Input)+1)-stpos) As Item
    FROM Split
)