Arduino communication to Raspberry Pi using HC-05
port_2 = serial.Serial(" is most likely a copy and paste error on your part, but needs to be fixed if you want 2 serial ports to deal with
You only read from port in your Python while loop without touching port_2. This is the reason you only see output from one serial port
You should use a robust serial data packet-system. Right now you have no way of ensuring that the data received in Python is corrupt or not. You can easily use the pip-installable Python package pySerialTransfer and compatible Arduino library SerialTransfer.h (installable via the Arduino IDE's Libraries Manager).


For theory behind robust serial communication, check out the tutorials Serial Input Basics and Serial Input Advanced.