BUG #2103: System column oid is not unique

The following bug has been logged online:

Bug reference:      2103
Logged by:          wangshj
Email address:      wangshj@sduept.com
PostgreSQL version: 8.1.0
Operating system:   CentOS 4
Description:        System column oid is not unique
Details:

The following is my test.

oidtest=# CREATE TABLE oidtest( name text ) WITH OIDS;
CREATE TABLE
oidtest=# INSERT INTO oidtest ( name ) VALUES( 'name1' ) ;
INSERT 54512 1
oidtest=# COPY oidtest (name) WITH OIDS FROM stdin;
Enter data to be copied followed by a newline.
End with a backslash and a period on a line by itself.

>>>> 54513        copyname
>>>> \.

oidtest=# INSERT INTO oidtest ( name ) VALUES( 'name2' ) ;
INSERT 54513 1
oidtest=# SELECT oid,name from oidtest ;
  oid  |   name
-------+----------
 54512 | name1
 54513 | copyname
 54513 | name2
(3 rows)

oidtest=#
Then I got two records with same oid(54513).

In the second test, I created two tables and added primary key (oid) to
them. As below:

oidtest=# CREATE TABLE oidtestpk (name text, PRIMARY KEY (oid) ) WITH OIDS
;
NOTICE:  CREATE TABLE / PRIMARY KEY will create implicit index
"oidtestpk_pkey" for table "oidtestpk"
CREATE TABLE
oidtest=# CREATE TABLE oidtestpk_another (name text, PRIMARY KEY (oid) )
WITH OIDS ;
NOTICE:  CREATE TABLE / PRIMARY KEY will create implicit index
"oidtestpk_another_pkey" for table "oidtestpk_another"
CREATE TABLE
oidtest=# INSERT INTO oidtestpk(name) VALUES ('name0');
INSERT 54562 1
oidtest=# COPY oidtestpk(name) WITH OIDS FROM stdin;
Enter data to be copied followed by a newline.
End with a backslash and a period on a line by itself.

>>>> 54564        copyname64
>>>> \.

oidtest=# INSERT INTO oidtestpk_another(name) VALUES ('name63');
INSERT 54563 1
oidtest=# INSERT INTO oidtestpk_another(name) VALUES ('name64');
INSERT 54564 1
oidtest=# SELECT oid,name FROM oidtestpk where oid=54564;
  oid  |    name
-------+------------
 54564 | copyname64
(1 row)

oidtest=# SELECT oid,name FROM oidtestpk_another where oid=54564;
  oid  |  name
-------+--------
 54564 | name64
(1 row)

And then I got records with same oid(54564).
Is it a bug?