Batch    Sample    Value
0        0         A
0        1         A
1        0         A
1        1         B
2        0         B
2        1         B
...

Batch Different
0     FALSE
1     TRUE
2     FALSE
...

select 	Batch, 
	case when (select count(*) from tbl x where x.Batch = t.Batch) = 
                  (select count(distinct(Value)) from tbl x where x.Batch = t.Batch) then 
		'TRUE'
		else
			'FALSE'
		end as Different
from	tbl t
group by Batch

CREATE TABLE YourTable(Batch int, [Sample] int, Value char(1))

INSERT INTO YourTable
SELECT 0, 0, 'A' UNION ALL
SELECT 0, 1, 'A' UNION ALL
SELECT 1, 0, 'A' UNION ALL
SELECT 1, 1, 'B' UNION ALL
SELECT 2, 0, 'B' UNION ALL
SELECT 2, 1, 'B'

SELECT 
	Batch, 
	Differnt = 
		CASE 
			WHEN COUNT(Batch) = 1 THEN 'FALSE' 
			ELSE 'TRUE' 
		END
FROM
(
	SELECT DISTINCT Batch, Value
	FROM YourTable
) t
GROUP BY Batch

DROP TABLE YourTable