try this
if exists (select * from K_RT_AmountReceived where trno=@trno)
begin
if exists(select *from K_RT_AmountReceived where trno = @trno and recamount = @recamount)
begin
select '2' as status
end
else
begin
insert into K_RT_AmountReceived(partyname,[date],recamount,chequeno,trno,updatedby,updatedon)values(@partyname,@date,@recamount,@chequeno,@trno,@username,getdate())
select '1' as status
end
end