nothing to worry about brother. i had the same issue when i bought my car. got it registered from Karachi and when i got the book, i noticed the wrong engine number. took a data correction form, filled it and the issue was solved. nothing to worry about and no need to pay bribes to the agents there.
but if they are not correcting it, you might have to pay or should have a good reference with someone. sadly this is how things work in our country