ON THE OFFENSIVE STANCE, the counsel of the accused can always say that the cheque (in question) was stolen or lost or misplaced and the complainant took advantage and forged the signature of the accused, HENCE the difference in signature of the accused.
HOWEVER, " I F " the complaintant can prove that the accused is a chronic & habitual violator of the N.I.Act and deliberately issues cheque with signature variations, THEN the complaint ALSO can be filed u/s 420 IPC and another u/s 138 of the N.I.Act. FOR this the complainant will have to obtain Bank Statements of the Accused's account alongwith other false-signature cheques of the accused. For evidence other inputs in the cheque (date, payee name, words and figures) must match the hand-writing of the Accused, to nail him. Also to get bank statement of accused to prove that his account had in-sufficient balance to honour cheque and that accused coerced bank to return cheque due to "signature mismatch".
All documentary evidences required for this and the onus of it is on the Complainant to prove all above, to invoke process of summons.
FURTHER, " I F " there is a genuine signature difference of the accused on his cheque AND IF there is sufficient balance in the account of accused, THEN the provisions of the N.I.Act CANNOT be invoked.
Keep Smiling .... Hemant Agarwal