create table [ParamPairs] (
    [id] int idenity(1,1)
   ,[Param1] varchar(50) not null
   ,[Param2] varchar(50) not null
   ,constraint [PK_ParamPairs] primary key clustered ([Param1],[Param2])
)

select p.*
from ParamPairs p
join ParamPairs p1 on p.Param1 = p1.Param2 and p.Param2 = p1.Param1

select P1.id, P1.Param1, P1.Param2, P2.id as [2 id], P2.Param1 as [2 Param1], P.Param2 as [2 Param2]  
from ParamPairs P1 INNER JOIN ParamPairs P2 ON P1.Param1 = P2.Param2 And P1.Param2 = P2.Param1

SELECT T.[ID],T.PARAM1,T.PARAM2
FROM PARAMPAIRS T
WHERE EXISTS
(
  SELECT 1 FROM PARAMPAIRS T1
    WHERE T.PARAM1=T1.PARAM2 AND T.PARAM2=T1.PARAM1
)

P2.Param2 as [2 Param2