Serving Notice Period during Probation

Hi, It will be so grateful if I got a solution to my concern. I have passed my resignation in probation mentioning notice period of 1 month. But I was asked to serve 2 months notice period as a reply e-mail. I have signed my appointment letter and it states the relevant clauses. 1.Probation Period You will initially be on probation for a six (6) month period, which may be extended or reduced at the sole discretion of the Management. After successful completion of probation, you will continue as a regular employee. In case your performance is not found satisfactory during the period of probation, including extended period of probation, if any, your services will stand terminated on expiry of such period of probation and you will be informed of the same in writing. 2.Notice Period In the event of your desire to leave the employment of the Company or the Company's decision to terminate your services under Clause & sub clauses of 13 above, the duration of the Notice Period shall be two Month or Salary in lieu thereof on either side. Before leaving the Company, you will properly hand over charge / control of all Company assets, documents etc. in your possession to the authorized relieving person. All claims against SMEC must be submitted within a month of leaving the office and no claim thereafter will be entertained by the Company. Am I legally bounded by 2 months notice period? If not please suggest how to defend.