Ya is it possible to share a single net connection , even airtel is encouraging this ,All you need is a switch or hub (i thinks its around 700Rs, its better to use switch than hub) and 2 data cables .
just connect the output of your modem to switch ,now connect your PC's and switch with those 2 data cable .configure IP address ,DNS(opendns for better speed)...
If you have any problme contact customer care they will help you ...
But your bandwidth will be shared if both the system are using net at same time .your net speed will be shared only when ,both the user and accessing net (i.e only when you download )