Hi, 

Trying to import translation in Odoo 12, i get the following error : 

ERROR: ON CONFLICT DO UPDATE command cannot affect row a second time
HINT: Ensure that no rows proposed for insertion within the same command have duplicate constrained 
values.

i did some research and found out that postgres included On Conflict to 'Upsert' a record. 
That is to say : when you insert a new row into the table, PostgreSQL will update the row if it already exists, otherwise, PostgreSQL inserts the new row. 

See http://www.postgresqltutorial.com/postgresql-upsert/ for more details. 

In my case, what should i do so that i can import translation successfully ?

Thank you.