Totally agree with @expert_sg and @nayakp. Regarding cloning it depends on the card and its security. For example, if you are talking about a 125KHz proximity card, there is literally no security or keys and can easily be cloned. If you take Mifare Classic, it has only 6 bytes key with Crypto1 algorithm and pretty easy to clone for an expert. And if you consider, for example Desfire EV2/EV3 or Cipurse, this is little more advanced and supports AES keys and advanced security featues and little hard to clone