Gör det
CONCAT(import.nume,' ',import.prenume) full2
istället för
import.CONCAT(nume,' ',prenume) full2
Uppdatera
Prova det:
SELECT t1.*, CONCAT(t1.nume,' ',t1.prenume) full2
FROM import t1
INNER JOIN (SELECT CONCAT(i2.nume,' ',i2.prenume) `full`, COUNT(*)
FROM import i2
WHERE i2.users_id=1
GROUP BY `full`
HAVING COUNT(*)>1) as t2 ON full2 = t2.`full`
WHERE users_id=1