@bencyp, your topic has been moved to a more suitable location on the forum. Installation and Troubleshooting is not for problems with your project 
See About the Installation & Troubleshooting category.
It's not quite clear to me if you want to send SMSes from both NodeMCUs or receive he same SMS on both NodeMCUs.
If the latter, below is one way that might work.
Decide which NodeMCU will control the GSM; that one will issue the commands. The second one will only listen on the serial interface and not issue commands to the GSM (do not connect the TX line of it, only the RX).
Another way is to let one NodeMCU communicate with the other one; and only one will communicate with the GSM. I'm not familiar with ESP8266 so can't tell you which options there are; another serial port, I2C, SPI, ...