If there are really lots of duplicates, I'd recommend to recreate the table with only the clean data:
CREATE TABLE tmp AS
SELECT id, name, surname, max(d) as d
FROM t
GROUP BY id, name, surname;
and then replace the original table with the original table:
RENAME your_table TO old_table;
RENAME tmp_table TO your_table;
Don't forget to move indexes, constraints and privileges...