Strange bug

I just noticed that I accidentally got a duplicate id. My
definitions are here:

CREATE TABLE citations (
citation_id INTEGER PRIMARY KEY,
source_fk INTEGER REFERENCES sources (source_id)
);

CREATE TABLE relation_citations (
relation_fk INTEGER REFERENCES relations (relation_id)
) INHERITS (citations);

ALTER TABLE relation_citations
ADD CONSTRAINT source_relation_citation UNIQUE
(source_fk, relation_fk);
CREATE INDEX cit_relation_key ON relation_citations (relation_fk);

CREATE TABLE event_citations (
event_fk INTEGER REFERENCES events (event_id)
) INHERITS (citations);

ALTER TABLE event_citations
ADD CONSTRAINT source_event_citation UNIQUE
(source_fk, event_fk);
CREATE INDEX cit_event_key ON event_citations (event_fk);

And here is the accident:

pgslekt=> insert into relation_citations values (64062,4578,20017);
INSERT 1478990 1
pgslekt=> insert into relation_citations values (64062,4578,20018);
INSERT 1478991 1

I got an error when I transferred the data to my Web database running
MySQL:

ERROR 1062 at line 19839 in file: 'ss_relation_citations.sql': Duplicate
entry '64062' for key 1

How can this happen?
--
Leif Biberg Kristensen | Registered Linux User #338009
http://solumslekt.org/ | Cruising with Gentoo/KDE