What issues I might face calling memory allocators twice or more?

I am just initializing the following:

myVar = [[NSMutableDictionary alloc] init];

The app keeps crashing for the users with the following (crashlytics):

EXC_BAD_ACCESS KERN_INVALID_ADDRESS at 0x00000000100000000

I might be calling the above more than once for the same variable. can you please help me out?