validation and duplicate update() in laravel

In my form Voiture, I want to do a validation system for the fields immatriculation and num_vehicule

Here i an overview:

If I edit the first recording ie the value of the field num_vehicule 000001 per 0000032and that I validate, I have an error message because the value of the field immatriculation already exists.

I don't understand the problem... Do you have an idea please?

'immatriculation' => 'required|string|max:15|min:6|unique:voitures,immatriculation',
'num_vehicule' => 'required|string|max:6|min:6|unique:voitures,num_vehicule',
'fk_modele' => 'required'

Thank you

via Chebli Mohamed