In Government Job, your employer whoever that Department will ask you to submit Caste Validity Certificate which is mandatory. Better you apply for it now. If in your father Caste certificte doesn't match with your caste certificate then you won't be able to get Cast Validity. Thereafter, you will get to know where exactly is fault. Once you get caste certificate of Khatik, it is wrong because while submitting application for issuing caste certificate you must I have tendered affidavit that if the information is false then I will be reasponsible under Section 190 of IPC. My advice would be first properly check whether mistake happned and where it happen. Thereafter, you should ask the Collector to correct the certificate. Because, once you applied for issuing caste certificate of Khatik you cannot say no no I don't belong to Khatik, I belong to some any other caste. So, now you should apply for caste validity certificate then you will get to know if there is mistkake, who's mistake and how to cure it.