SELECT contratosfianzas.adquisicion_contrato, count(*) as no_ope
From contratosfianzas
GROUP BY contratosfianzas.adquisicion_contrato
HAVING count(*) > 1

from b in db.contratosfianzas
group b by b.adquisicion_contrato into grup
where grup.Count() > 1
select grup.Key, grup.Count()