When using BTStack att_read_callback handler runs twice per read request

Question

Firstly I'm extremely new to BLE in general so i may be using the wrong terminology, please mention if i do so i can learn.

I'm using the BTStack library on an ESP32 to communicate with a web app ive written and got some odd behaviour.

When requesting a value from a connected characteristic the att_read_callback handler to service the request runs twice, but the web app only receives a single response.

Iv'e tested running the att_delayed_response example from BTStack here

Iv'e tried my own simple variation of this which can be viewed Here

Iv'e tried connecting with my webapp and a simple BLE app on my smart both and both times the read callback is executed twice.

I'm at a loss why this is happening. It doesn't cause any stability issues but im trying to build a foundation to build more complex apps upon so this seems like a fundamental issue i need to understand.

On the ESP side i create the server just as in the docs using the generate profile data from the .gatt file

att_server_init(profile_data, att_read_callback, att_write_callback);

and my read callback looks like this

static uint16_t att_read_callback(hci_con_handle_t connection_handle, uint16_t att_handle, uint16_t offset, uint8_t * buffer, uint16_t buffer_size){
  UNUSED(connection_handle);

  printf("\n\nIm Hit\n\n");

  // This is our auto generated attribute UUID handle. This is how we check the read came from characteristic A vs B
  if (att_handle == ATT_CHARACTERISTIC_0000FF11_0000_1000_8000_00805F9B34FB_01_VALUE_HANDLE){
    // Get the value to send to the connected device by executing our onRead callback
    const char * response = onReadCallback();
    
    return att_read_callback_handle_blob((const uint8_t *)response, (uint16_t) strlen(response), offset, buffer, buffer_size);
  }

  return 0;
}

Im Hit gets logged twice per read request.

There is so much configuration going on with advertisement data and GAPconfiguration it difficult for me to pin down the exact relevant code.