For suppose I got 3 or 4 iim calls. Can i attend any two of them?? It means if I I not get at first Iim is there any chance to go next one?
By getting calls you mean call for second round of interview and WSAT. Yes definitely you can attend all the IIMs interview respectively. Not only 3 or 4 even 10 or more than that without any problem.
There is no restrictions on the interviews you can attend as every IIM works separately. Every IIM has its own parameters, different weightages, they make separate merit list and call students separately. So you don't need to worry about it at all.
Even after interviews most of us get admission offer from so many IIMs but again we choose the best one and reject others. You must have an idea that apart from the direct admission offer after final merit list even students are given waiting list which moves on when a final merit list student rejects the offer. Like I got offer from IIM Kozhikode and Indore. I rejected Indore and joined Kozhikode so a waiting list in IIM Indore would have moved up.
In short you cam get unlimited interviews and get selected in unlimited colleges but will need to select one best college in the end.
All the best!!

Along with this you need to start preparing for WSAT and interview. Questions asked in interview has no limits it can be asked from anywhere about anything so it's not easy at all until you learn how to drive an interview. You need to update yourself with all recent happenings improve your general knowledge you need to know about yourself very well from starting to ending because they will be exploring you only and finally you need to learn how to drive an interview in your favour.
So yes you have lots of work but I will say to focus on exam right now which is on Sunday then we can work on it.
All the best for exam.