`INSERT` does not add duplicate rows

[penberg]

SQLite:

sqlite> CREATE TABLE users (id INT, username TEXT);
sqlite> INSERT INTO users VALUES (1, 'penberg');
sqlite> INSERT INTO users VALUES (1, 'penberg');
sqlite> SELECT * FROM users;
1|penberg
1|penberg

Limbo:

limbo> INSERT INTO users VALUES (1, 'penberg');
limbo> INSERT INTO users VALUES (1, 'penberg');
limbo> SELECT * FROM users;
|penberg
limbo>

[seonWKim]

Seems it will work as expected when this PR is merged

[arpit-saxena]

This works as expected on the main branch. @penberg this can be closed