Well, I just checked all of the documents again and engine number is same even on the book, receipts (that blue one which you get from Honda showroom) and even on the original registration papers which you fill for applying for Reg. number. Its the same and not tampered with.
SER_GTR, Yes sir, wires are Osakad and Nittoed for CNG/Headlight Relays/Foglights etc but surely its the same engine.
Huzaifaa, No offense taken at all, one should know what he is buying/looking at.