Very odd order by behavior

FreeBSD 4.2, PostgreSQL 7.0.3

The attached file is the schema and data to the app_degrees table. Now check
this out :

select * from app_degrees gives (expected) :

degree_id | abbr | description
-----------+--------+------------------------------------------
1818 | ACC | Accounting [ACC]
1819 | ACD | Acoustics [ACD]
1820 | ADV | Advertising [ADV]

select * from app_degrees order by abbr ASC gives :

degree_id | abbr | description
-----------+--------+------------------------------------------
1818 | ACC | Accounting [ACC]
1818 | ACC | Accounting [ACC]
1819 | ACD | Acoustics [ACD]
1819 | ACD | Acoustics [ACD]
1820 | ADV | Advertising [ADV]
1820 | ADV | Advertising [ADV]

Either I'm seeing double or something isn't right here :-)

Thanks for any insights.

-Mitch