No, MID (Merchant ID) This is a unique identifier provided to every merchant by Paytm. MID is part of your account credentials and is different for staging and production environments.
Merchant key is used to generate and verify checksum. It is also part of the account credentials and provided by Paytm and is different for staging and production environments. But this should not be sent in any parameter to Payment gateway. This needs to be kept on server side and should not be shared with anyone.