Error in RFNOC blocks in CPP ?? Cannot create! Property already exists at: /blocks/0/DUC#0/noc_id

[sp h]

when I want to convert a GRC python code to CPP code I am faced with NOC graph error?

any idea for solving the problem...?  I too attached python code...

[ERROR] [RFNOC::GRAPH] Caught exception while initializing graph: RuntimeError: Cannot create! Property already exists at: /blocks/0/DUC#0/noc_id

terminate called after throwing an instance of 'uhd::runtime_error'

what(): RuntimeError: Failure to create rfnoc_graph.

 const::uhd::device_addr_t device("addr=192.168.10.2");

        gr::ettus::rfnoc_graph::sptr rfnoc_graph_ctrl=gr::ettus::rfnoc_graph::make(device);

        uhd::stream_args_t stream_arg=uhd::stream_args_t("fc32","sc16");

        gr::ettus::rfnoc_rx_streamer::sptr rx_streamer=gr::ettus::rfnoc_rx_streamer::make(rfnoc_graph_ctrl,1,stream_arg,1,true);

        gr::ettus::rfnoc_rx_radio::sptr rx_radio=gr::ettus::rfnoc_rx_radio::make(rfnoc_graph_ctrl,device,-1,-1);

        rx_radio->set_rate(2000);

        rx_radio->set_antenna("AB", 0);

        rx_radio->set_frequency(25e6, 0);

        rx_radio->set_gain(10, 0);

        rx_radio->set_bandwidth(0, 0);

        rx_radio->set_dc_offset(false, 0);

        rx_radio->set_iq_balance(false, 0);

        gr::ettus::rfnoc_ddc::sptr  ddc=gr::ettus::rfnoc_ddc::make(rfnoc_graph_ctrl,device,-1,-1);

        ddc->set_freq(0, 0);

        ddc->set_output_rate(0, 0);

        //Connections

        rfnoc_graph_ctrl->connect(ddc->get_unique_id(), 0,rx_streamer->get_unique_id(), 0, false);

        rfnoc_graph_ctrl->connect(rx_radio->get_unique_id(), 0,ddc->get_unique_id(), 0, false);

        tb->connect(rx_streamer, 0,tsnk_c , 0);

        tb->connect(rx_streamer, 0,fsnk_c , 0);

        tb->start();

rfnoc_getting_started.py
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