If I receive data at the same time for 2 ports at the same time will be lost?
Since nothing happens at exactly the same time, no.
Each serial port has its own record or buffer?
Yes.
Or Is There a library to use 2 serial ports at a time and that can receive data at a time?
Yes. It's called HardwareSerial. Serial, Serial1, Serial2, and Serial3 are all instances of that class.