Can I do two 220V on a single line?
Can I do two 220V receptacles on a single 20A line?


Yes, you can.


  The equipments will be drawing max 3A and 13A. Is it possible to both on a same line?


Yes, even if they are continuous loads 16 amps would be allowed.


  Can I also use 12/2 cable? or should I use 12/3?


12/2 is all you need


  Can these receptacles placed in a double outlet box?


Yes.

You can put as many receptacles as you like on a circuit in residential applications. 240 volt receptacles only require 2 wires and a ground wire. Hence the 12/2 wire is sufficient. Circuits are required to be sized for the load they serve. Continuous loads are required to be sized at 125% of the load served. Devices can be placed in the same box without dividers unless the voltage exceeds 300 volts between devices. Which does not happen in residential applications (here in the US anyway).

Good luck!