The same sequence generator is used in case of multiple columns

WITH serial_columns AS (SELECT c.table_schema, t.table_type, c.table_name , c.column_name, coalesce(c.column_default, d.domain_default) AS column_default
FROM information_schema.columns c LEFT JOIN information_schema.domains d USING (domain_schema, domain_name)
INNER JOIN information_schema.schemata s ON c.table_schema=s.schema_name
INNER JOIN information_schema.tables t USING (table_schema, table_name)
WHERE coalesce (c.column_default, d.domain_default) LIKE 'nextval%'
AND (c.table_schema = 'public'
OR s.schema_owner<>'postgres')),
sequences AS (SELECT sc.table_schema, sc.table_type, sc.table_name , sc.column_name, s.sequence_schema, s.sequence_name
FROM serial_columns AS sc, information_schema.sequences AS s
WHERE column_default ILIKE '%' || 'nextval(''' || s.sequence_name || '''::regclass)' || '%' OR
column_default='nextval(''' || s.sequence_schema || '.' || s.sequence_name || '''::regclass)')
SELECT sequence_schema, sequence_name, Count(*) AS number_of_uses, string_agg(table_type || ': ' || table_schema || '.' || table_name || '.' || column_name, ';<br>' ORDER BY table_schema, table_name) AS columns
FROM sequences
GROUP BY sequence_schema, sequence_name
HAVING Count(*)>1
ORDER BY sequence_schema, sequence_name;