pan card

Immediately surrender one Pan card no else Liable to pay penalty up to Rs. 10000
You can write a letter to your jurisdictions to cancel one. I think even online options are also available?

If the PAN number in both the cards are different, then you will have to surrender one of the PAN Number as soon as possible.

It’s illegal for a person or company to have more than one PAN Number. If caught, Income Tax Department can take a legal action or put financial penalties.

As this happed accidently with you, here are ways to surrender the duplicate PAN Number:

Manually Submitting the ApplicationWrite a letter to this effect to the assessing officer under whose jurisdiction you have been filing your returns. The letter must contain details such as your name, contact details, details of the PAN Card to be retained, details of the duplicate PAN Card(s) which you need to surrender, etc.Keep the acknowledgement copy of the letter that you have filed with the I-T department, stating that you are surrendering your additional PAN.That is sufficient as proof of surrender and no additional confirmation from the I-T authorities is required.On receipt of the acknowledgement, there is no need for you to wait for intimation from the income tax department considering that the PAN submitted has now been cancelled by them.The acknowledgment copy of the letter submitted will more than solve the purpose.Manually Fill the Form No. 49A for change/Correction in correction in PAN and submit the same at your nearest UTI pan centers or NSDL TIN Facilitation centers. See point no. 10 in that form where you can fill the additional PAN number you want to cancel. Tick the box in front of point No 10.OnlineApplication

Visit NSDL website using followinglink and fill the detail in the Change Request Form:

https://tin.tin.nsdl.com/pan/

while making application you need to submit an affidavit stating that you didn't carry out any transactions with the pan that you want to deactivate