About submission of undated blank cheques as a security deposit

I have got an offer from a private company. In the agreement they have written that during the firsth 3 months of training if I leave the job then I need to pay my training expenses + (number of months * salary per month). After that if I leave during probation period i.e next 6 months then I need to pay 12*probation period salary. After that if I resign without giving 6 months' notice then I need to pay 6*salary per month. Otherwise after 9 months I can leave without paying anything( if I serve the complete notice period) and after 3 years my, they have mentioned the date, the bond will be finished and I can resign any day. Now they are asking for two undated cheques. Though in agreement they haven't written whether it should be blank or filled, but I came to know from some of the employees of that company that they take two blank cheques enclosed with the agreement. Now I want to ask that giving two undated blank cheques, how safe is that from my side? I asked some of the ex-employees of that company they said they left the company breaking the bond, closed the acount from where the cheques were drawn, but still they have done nothing. But if they do something then how much can they do? Can they misuse my cheques even if I follow every point in my contract?