feature <>'A' had the admincode2 same as the geonameid, probably it was a ADM2 before

number of errors=0
number of warnings=0

select geonameid,ansiname,featurecode,countrycode,admincode1,admincode2 from geoname where featureclass<>'A' and admincode2=geonameid::text and admincode2 is not null

geonameid	ansiname	featurecode	countrycode	admincode1	admincode2