nRF52833 --MESH DFU---there is show "New firmware" message after update with dfu.....

Question

I test dfu with two board, detail as follow: 
 First step:: create files needed follow document 
 Second step:: flash files to board 
 ** EV board: (as receive data via serial from PC and sent) 
 1）nrfjprog --program s113_nrf52_7.0.1_softdevice.hex --chiperase 2）nrfjprog --program mesh_bootloader_serial_gccarmemb_nrf52833_xxAA.hex 3）nrfjprog --program application_file/NoMe_dfu_nrf52833_xxAA_s113_7.0.1.hex 4）nrfjprog --program device_page_nrf52833_xxAA_s113_7.0.1.hex 
 
 **other board developed by us: 
 1）nrfjprog --program s113_nrf52_7.0.1_softdevice.hex --chiperase 2）nrfjprog --program mesh_bootloader_gccarmemb_nrf52833_xxAA.hex 3）nrfjprog --program V0510_sensor_server_nrf52833_xxAA_s113_7.0.1.hex 4）nrfjprog --program device_page_nrf52833_xxAA_s113_7.0.1.hex 
 Third step:: make DFU file 
 nrfutil dfu genpkg --application V0511_sensor_server_nrf52833_xxAA_s113_7.0.1.hex --company-id 0x53594332 --application-id 1 --application-version 2 --key-file private_key.txt --sd-req 0x00CC --mesh V0511_V2.zip 
 nrfutil dfu genpkg --application V0512_sensor_server_nrf52833_xxAA_s113_7.0.1.hex --company-id 0x53594332 --application-id 1 --application-version 3 --key-file private_key.txt --sd-req 0x00CC --mesh V0512_V3.zip 
 
 Fourth step: update 
 
 nrfutil --verbose dfu serial -pkg V0511_V2.zip -p COM5 -b 115200 -fc --mesh 
 
 Fifth step: 
 
 when finish ,there is " DFU END " message showing, now the system works well 
 but when I power off two board, then power on together, there is show "New firmware" message, 
 why will " "New firmware" message " show, since I do not do " nrfutil --verbose dfu serial -pkg V0511_V2.zip -p COM5 -b 115200 -fc --mesh" command again? 
 if only power on one of them , there is no "New firmware" message. 
 
 could you help me , please?