select (a.surname||' '||a.lastname||' '||a.patronymic) as fio
from tariff_plan t
inner join abonents a
inner join subscriber_base d on a.id_abonent = d.abonent_id
inner join personal_account p on d.id_contract = p.contract_id
on t.id_tariff = p.tariff_id and t.id_tariff=4
where p.date_entry>=date_trunc('month',current_date-interval'1'month)
and p.date_entry < date_trunc('month',current_date)
Group by fio
having count(*)>1