A Project with many .ino files (sketch).

https://github.com/WorldFamousElectronics/PulseSensor_Amped_Arduino/tree/master/PulseSensorAmped_Arduino_1dot4

There are 4 .ino file. And I open them in Arduino IDE and there are 4 instances of IDE popped up.

They look like they are indepedent. But no they all related.

When I upload the file to Arduino, I can only do one instance (.ino) at one time.

It seems kind of odd why 4 different .ino files and each one opened separately in IDE.

Did you follow the detailed installation instructions at GitHub - WorldFamousElectronics/PulseSensor_Amped_Arduino: PulseSensor Arduino code for BPM and Processing-Visualizer?