Each different MPU6050 should have a different address (MPU_ADDR in the attached code) on the I2C bus.
Edit: In the Arduino playground, they suggest an interesting trick to read more than 2 MPU6050:
If your 10 AD0 lines are connected to 10 different pins set to high (3.3V), so every MPU-6050 is I2C address 0x69. BUT you decide in your code to read only the device at address 0x68, and for that you set one and only one pin to a low level (GND) to give this device the address 0x68.
So every sensor is used at I2C address 0x68 (one by one) and 0x69 is never used.
Make sure that your sensors don't have builtin pull ups if you use SDA/SCL, otherwise use SDA1/SCL1 and replace everywhere in your code Wire by Wire1.