At the end, i decided to give some gap between transmitters. So, 36 to
90 and -36 to -90 are assigned to transmitters. But, result is same. I
have attached two pictures of spectrum. They represents state of one and
two transmitters are active. You can check the situation from there.
I'm not familiar with the details of OFDM systems but that looks like quite adequate separation in the spectrum. Therefore, it seems to me that the problem is most likely your receiver's filter — it is not adequately selecting one signal and not the other. Consider visualizing the output of your low pass filter, and telling us what blocks and parameters you are using.