how to clone sim card

You don't

It is not possible to have the same number on 2 phones. That has nothing to do with SIM cards. When you put a SIM card in a phone and turn it on your carrier adds the IMEI of your phone to its database. If you move the SIM card (or put an illegal copy of it) in another phone then that phone’s IMEI will be added to the carrier’s database, replacing the previous IMEI. So there will always be only one phone with a phone number.

You can achieve what you want by subscribing to Google Voice, which is free. Your one GV number can ring on multiple phones, and, using the GV app on your phone, you can make calls using your GV number.

RavenaB wrote:

But it is possible to duplicate sim cards

Possible… yes. Legal… No.

As Lawrence Finch explained, your carrier doesn't allow what you're trying to do. If you tried it repeatedly, there's a good chance your carrier would suspend your account entirely.