Monitoring 2 SPO2 signals using module afe4490

I'll take another look, but it may be a while.
What variable are you accessing to determine the heart rate?

Edit: Looks like

data_modul1.RED_data

The heart rate should be

data_modul1.heart_rate

yes I used that variable to generate the heart rate

data_modul1.heart_rate

The output you are getting is the same value for each of the 2 sensors?
Look in your library for this file.
protocentral_hr_algorithm.cpp
The variables defined might need to be moved to the typedef.

unsigned long peakWindowHP[21], lastOnsetValueLED1, lastPeakValueLED1;
unsigned char HR[12];
unsigned char temp;
unsigned int lastPeak,lastOnset;
unsigned long movingWindowHP;
unsigned char ispeak=0;
unsigned char movingWindowCount, movingWindowSize, smallest, foundPeak, totalFoundPeak;
unsigned int freq;
unsigned long currentRatio=0;

I haven't tried to move the typedef, can you help me?

At some point, you must determine which is the most appropriate path to take. Even being retired, my time is not always free.
Maybe best to use one Arduino per sensor.
How many do you need?

I need 2 sensors, but I still want one arduino.

Previously you fixed the spo2 reading and used 3-state-buffer so that it can display the signals of both modules without colliding with the modified library. can I use 3-state-buffer so that the CS pins do not collide, but still use the original library, so that it can display the results of spo2, HR and the signals of both modules?