Any idea for two transmitters one receiver wireless communication module?
There's lots of different ways multiple transmitters can share a receiver or a medium.

Classically, we organize these in four categories:


Time-based multiple access (the different transmitters simply don't transmit at the same time)
Frequency-based multiple access (information is coded onto oscillations of different frequency, which don't interfere with each other)
Spatial multiplexing (the receiver is able to tell signals coming from different directions apart)
Code multiplexing (You find sets of functions which are orthogonal under some dot product, and each of your transmitters uses a different one. The superposition of multiple signals can be losslessly deconstructed into the original data by applying that dot product)


All these methods work with any signal – they're most prominently used in digital radio communication, but there's no reason why Code Division would not work for e.g. infrared comms. In fact, I think there's multiple IR data communication standards that do that. And, for example, infrared remote controls avoid interference with normal sources of light (like lightbulbs) and other infrared-based comm systems by employing basically frequency division principles. 

I'd drop the laser idea – a laser typically generates a focussed beam, and you don't need that – a simple LED that illuminates a larger region is much easier to handle.