Can we configure two digital pins as serial pins using software serial library?
Kind of, yes - however you can't use them both at once. SoftwareSerial is blocking. That is, while one port is receiving or sending data the other port will be completely locked out so won't be able to receive anything. So it kind of breaks it in a nasty way.
Personally I never advocate the use of software serial unless there is absolutely no choice whatsoever, and that is something I have never found.
If you need more than one UART then pick a chip with more than one UART.