The word Naam here means Sifaati Naam i.e. qualitative names of Vaheguru and it does not mean that one Makhsoos Gurmat Naam is not valid. This Pankiti means that since Vaheguru jee has "Roop Ananta" i.e. many forms, His Naams (names given to praise his one or two qualities) too are many.
Gurbani Agam Agaadh Bodh hai.
Kulbir Singh
ਸਤਿਗੁਰਬਚਨਕਮਾਵਣੇਸਚਾਏਹੁਵੀਚਾਰੁ॥