Primary Key Problems

Here is a good one.  I have three fields set for my primary key.  Now I
thought that a primary key was unique, and dups can not be inserted.

CREATE TABLE "inventory" (
        "stock" character varying(50) NOT NULL,
        "inventory_type" character varying(20) DEFAULT 'unknown' NOT NULL,
        "client_id" integer NOT NULL,
[...]
        Constraint "inventory_pkey"
        Primary Key ("stock", "inventory_type", "client_id")
);

and I insert into the db and get dups.

 client_id | stock | inventory_type
-----------+-------+----------------
        81 | 2001  | new
        81 | 2001  | new
        81 | 2003  | new
        81 | 2005  | new
        81 | 2006  | new
        81 | 2006  | new
        81 | 2008  | new
        81 | 2008  | new

Why did I get dups in my data?

PostgreSQL 7.1.3 on i686-pc-linux-gnu, compiled by GCC 2.95.4

Thanks.

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hurlingdown the highway" Andrew S. Tanenbaum) 
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