there are 2 ovaries then there will be also two ovulation releasing two ova but if only one ovum is utilised in fertilisaton then where does one ovum go ???

in the book there is written that only a single ovum is released into the tube during the ovulation,,but i didn't understood what will happen to the ovum from next ovary.number of ovary is two then there will be also two ovulation releasing two ova but if only one ovum is utilised in fertilisaton then where does one ovum go????????????this can be possible only if there are some factor that prevent the ovulation in one ovary when one is going in other ovary but if this really happens then what are those factors????