What does LEFT JOIN return when there are duplicate rows in the tables

The example contains two tables — t1 and t2, with repeating values. It is necessary to determine which set of rows will be obtained after executing the following query.

t1  t2
1  1
1  1
1  1
2  3
2  3
  2
  2

select * from t1 left join t2 on t1.x = t2.x