Asked about the indentity in SQL server 2000

I have created a table that a column is the primary key that is defined is idUser properties is indentity (1.1), and the other is a column with unique username.

Code:
create table Users (
int indentity idUser (1.1) primary key,
usename varchar (20) not null unique,
.....
)

I made 3 insert
+ Questions with username as ' test ' then-success-> idUser = 1
+ The second sentence also with username as ' test '--> errors
+ Third Sentence with username as ' test1 ' then-success-> idUser = 3

I would like to ask is how to idUser not 3, I like to be 2 because only have 2 lines are inserted.

I have written procedure has the transaction but the result is also like that, anybody help me, thank so much!!!