Problem with MPU6050 sensor

Using Arduino Sensors
1

I've connected two MPU6050 sensors to one Arduino UNO board, and connected the ADO pins to GND and 3.3V respectively. For some reason, both sensor values go to the same ADO value and whenever I wave the MPU6050 sensor a bit too much, both values go to 0 and don't move from there. What could be causing this issue?

here's the code I'm using:

#include <Wire.h>
#include <SoftwareSerial.h>
#include <MPU6050.h>
SoftwareSerial BTSerial(10, 11);

MPU6050 mpu1(0x68); // Address 0x68
MPU6050 mpu2(0x69); // Address 0x69

void setup() {
  Wire.begin();
  BTSerial.begin(9600);
  Serial.begin(9600);
  mpu1.initialize();
  mpu2.initialize();

  if (!mpu1.testConnection()) {
    Serial.println("MPU6050 #1 connection failed");
  } else {
    Serial.println("MPU6050 #1 connected");
  }

  if (!mpu2.testConnection()) {
    Serial.println("MPU6050 #2 connection failed");
  } else {
    Serial.println("MPU6050 #2 connected");
  }
}

void loop() {
  int16_t ax1, ay1, az1;
  int16_t gx1, gy1, gz1;
  int16_t ax2, ay2, az2;
  int16_t gx2, gy2, gz2;

  mpu1.getMotion6(&ax1, &ay1, &az1, &gx1, &gy1, &gz1);
  mpu2.getMotion6(&ax2, &ay2, &az2, &gx2, &gy2, &gz2);

  // Calculate angles (implement your own algorithm here)
  float angle1 = atan2(ay1, az1) * 180 / PI;
  float angle2 = atan2(ay2, az2) * 180 / PI;
  float relativeAngle = angle2 - angle1;

  Serial.print("Angle1: ");
  Serial.print(angle1);
  Serial.print(" Angle2: ");
  Serial.print(angle2);
  Serial.print(" Relative Angle: ");
  Serial.print(relativeAngle);

  if(relativeAngle<-70 && relativeAngle>-110) {
    Serial.println("one joint");
    //BTSerial.write("O");
  } 
  else if(relativeAngle<-130 && relativeAngle>-180) {
    Serial.println("two joint");
    //BTSerial.write("T");
  }
  else {
    Serial.println("no joint");
    //BTSerial.write("N");
  }

  delay(100);
}
2

When you test the MPU-6050, then please remove everything else from the sketch, such as the SoftwareSerial and the Bluetooth.

The most basic test is to use a multimeter (also called DMM). Can you check the voltages, and also the AD0 voltage on both modules.

The next basic test is to run a I2C Scanner sketch. Can you find such a sketch ? Try if you can make both modules visible on the I2C bus.
If a I2C Scanner does not see both modules, then you don't have to try a library.

You could have a counterfeit MPU-6050 chip, you could have a module with the wrong components, you could have a module with the wrong circuit (I think it is all three).

Solutions:
Do you have a 3.3V board ? That is easier when using 3.3V sensors. The MPU-6050 is outdated, can you buy a new sensor? Adafruit sells genuine sensors. Please don't use that library. Here is a straightforward library: https://github.com/jremington/MPU-6050-Fusion

Could you show a photo with the wiring ? Sometimes there are mistakes with breadboards. Beside that, breadboards can have bad contacts and jumper wires can be broken.