Maybe u need to save the "address" of the last connection in a global variable, and then, include a "if(address == old_addres ||old_addres == NULL) " in cb connection function.

Running this example : https://github.com/espressif/esp-idf/tree/master/examples/bluetooth/esp_ble_mesh/ble_mesh_sensor_model I'm trying to get data from 2 or more server-nodes, but I got it just from the last node connected. And I got the 2 followings "warnings" in terminal when the second node was...

Try to add the .h and .c files in src folder.