duplicate primary key

Hello.

I'm a bit shocked. During import/export of our database we've found a 
duplicate primary key.

# \d player
Table "public.player"       Column       |            Type             |                             Modifiers 


--------------------+-----------------------------+------------------------------------------------------------------------------------------------------------
id                | integer                     | not null default 
 
nextval('player_id_seq'::regclass)
...
Indexes:    "pk_id" PRIMARY KEY, btree (id)
...

# select * from pg_indexes where indexname='pk_id'; schemaname | tablename | indexname | tablespace |  indexdef
------------+-----------+-----------+------------+------------------------------------------------------ public     |
player   | pk_id     |            | CREATE UNIQUE INDEX 
 
pk_id ON player USING btree (id)

# select * from pg_constraint where conname='pk_id';
-[ RECORD 1 ]-+------
conname       | pk_id
connamespace  | 2200
contype       | p
condeferrable | f
condeferred   | f
convalidated  | t
conrelid      | 18319
contypid      | 0
conindid      | 18640
confrelid     | 0
confupdtype   |
confdeltype   |
confmatchtype |
conislocal    | t
coninhcount   | 0
connoinherit  | t
conkey        | {1}
confkey       |
conpfeqop     |
conppeqop     |
conffeqop     |
conexclop     |
conbin        |
consrc        |

# select count(*) from player where id=122224875;
-[ RECORD 1 ]
count | 2

The records are identical, besides ctid,xmin,xmax

# select tableoid,ctid,id,xmin,xmax from player where id=122224875; tableoid |     ctid     |    id     |    xmin    |
 xmax
 
----------+--------------+-----------+------------+------------    18319 | (9982129,2)  | 122224875 | 3149449600 |
3152681810   18319 | (9976870,49) | 122224875 | 3149448769 | 3152328995
 



I don't understand how this could have happened....

-- 
Best regards,
Alexander Pyhalov, 3152328995
system administrator of Southern Federal University IT department