Is it double pan card

Yes.Holding more than one PAN card is an offence under Income Tax Act and liable to 10000/- penalty.

She may Apply for deactivation of duplicate PAN Card

Yes... I agreed to Mr Eswar.,

Penalty imposed if Assessee have more than one PAN.

Is it duplicate card ? I don't think so. His son in law applied and got new regular PAN card.

Since both PAN cards belong to one individual, let new PAN card be surrendered to AO (give details in surrender request letter )

The AO then will carry out verification of records m mmand proceed to cancel PAN card.

Holding two PAN cards will invite penalty of Rs 10000/- .

The correct procedure is to apply for changes in old pan card and not a new PAN card.