MPU6050 + nRF24l01 + arduinopromini, 2nd channel doesn't work

Hi Everybody
I'm trying to build 2 wireless Accelerometer & gyroscope sensors, using twice (MPU6050, on an arduino pro mini, and nRF24l01 radio module) transmitters, to communicate with another nRF24l01 on an arduino uno as a receiver.
One channel works fine, but I can't make the second channel work.
I'm quite a newbie in coding, and there should be mistakes in my receiver code.
Can someone help me?

You will find as attached files the codes for the one channel version that works (nRF_I2C_transmit.ino, nRF_I2C_receive.ino), and the codes for the 2 channels version, that doesn't work (nRF_I2C_transmit_ch1.ino, nRF_I2C_transmit_ch2.ino, nRF_I2C_receive_2ch.ino)

Thanks a lot
Franck

nRF_I2C_transmit.ino (2.01 KB)

nRF_I2C_receive.ino (2.31 KB)

nRF_I2C_transmit_ch1.ino (2.09 KB)

nRF_I2C_transmit_ch2.ino (2.1 KB)

nRF_I2C_receive_2ch.ino (3.02 KB)