index problem when renaming a table

Hi ,

I used the command:

ALTER TABLE TEST_TABLE RENAME TO TEST_TABLE_01;

and tried to create a new one, based on the old, with some more fields.
But when I create the primary key, it says that it's name is already used
and it can't be dome, and exits.

Then I have to drop the old table's index, recreate it and create the new
table again. Isn't it a bug? Why can't I have the same name in 2 or more
tables in the same database? Or why PostgreSQL don't create a PK with
some random name (say PK_TBL01_1234) to each table so the index
name won't be duplicated?

TIA,
Ricardo.