you must remember mongoose motomags and supergoose were expensive ..........heros rode them ........so every kids had a mongoose decal as everybody wanted to be that hero...
so if they are genuine ............the fork steer tube will be marked as follows ....ie ....TANGE FI.......TANGE G2......ETCETC....
AS FOR other makers using decals or names close to mongoose ...then they would incur a infringment on copy rights and be dealt with ........