Can we have 2 HC12 on a single Arduino (1 to receive and other to transmit)?
Yes you can - one on Serial pins 0/1 and the other using SoftwareSerial on any other pins. Note that the one on SoftwareSerial will interfere with the one on Serial as it disables interrupts while sending or receiving.
It may be better to use an Arduino which has multiple hardware serial ports. Maybe one of the Teensy boards would be better for your needs.
Alternatively if (and I am not familiar with the modules enough to know if this is right or not) they operate as a transparent serial bridge then you could connect one module to the TX pin for transmission and the other to the RX pin for reception - reading from serial receives from one, and writing to serial transmits through the other.
Also note that you will have to ensure that both pairs of modules are running on different channels to prevent interference between them.