When using nRF MESH, two BLE event handlers being called


I have set a Mesh Client Node with two BLE services: Mesh Proxy Service and Nordic Uart Service. 

The problem is that when I send a message to the Mesh Client  from nRF Mesh app (for example, binding the Appkey, or the setting the publication address), two "on_ble_evt" handlers are being called: "mesh_gatt_on_ble_evt" (which is correct) but also "ble_nus_on_ble_evt", so the NUS service interprets the incoming packet as a NUS packet, while it is a packet for the Mesh service. 

¿Any idea of why this is happening?

Thank you