Can vibrations resistant PVC male and female disconnectors be used also as general PVC insulated male and female disconnectors, just because they are the same but of better quality?

Yes, it is true. ВРПИ vibration resistant disconnectors have an additional copper cuff, just like all brass disconnectors made by American and European manufacturers. The contact part of such a disconnector is made of brass that is only 0.4 mm in thickness. So the contact part after crimping is not that reliable like in lugs made of brass with 08.-1 mm in thickness.
Moreover, the copper cuff works for a safer connection even is the orientation of dies was chosen wrong.