F1020防火墙配置子接口IP地址报“IP地址冲突”

      正式线有多个公网相邻的公网IP地址，上架之前把相邻的公网IP地址都配置在防火墙的1/0/2【Untrust】接口及其子接口上，但发现配置了第一个公网IP之后，在子接口上配置第2个公网IP就报“IP地址冲突了”，这是什么原因呢？ 望知悉的朋友解析下。谢谢

1.  以下是我防火墙配置信息：

<H3C>dis version H3C Comware Software, Version 7.1.064, Release 9323P28

Copyright (c) 2004-2019 New H3C Technologies Co., Ltd. All rights reserved. 

H3C SecPath F1020 uptime is 0 weeks, 1 day, 1 hour, 19 minutes 

Last reboot reason: User reboot 

Boot image: flash:/f1000fw-cmw710-boot-R9323P28.bin 

Boot image version: 7.1.064, Release 9323P28 

  Compiled Apr 10 2019 16:00:00 

System image: flash:/f1000fw-cmw710-system-R9323P28.bin 

System image version: 7.1.064, Release 9323P28

 Compiled Apr 10 2019 16:00:00 

 SLOT 1 

CPU type: Multi-core CPU 

DDR3 SDRAM Memory 2046M bytes Board PCB Version:Ver.A CPLD_A Version: 2.0 CPLD_B Version: 4.0 Basic BootWare Version: 2.02 Extend BootWare Version: 2.02 Board PFC Version:Ver.A NandFlash PCB Version:Ver.A 

[SubSlot 0]16GE+8SFP (Hardware)Ver.A, (Driver)1.0, (Cpld)4.0

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2. 命令行配置结果报错

[H3C-GigabitEthernet1/0/2]dis this   【先配置了第一个公网IP正常】

# 

interface GigabitEthernet1/0/2 

 port link-mode route  

ip address 211.155.25.189 255.255.255.0 

# 

return

 [H3C]interface GigabitEthernet 1/0/2.1 

[H3C-GigabitEthernet1/0/2.1]ip address 211.155.25.190 255.255.255.0   #配置另外一个公网IP，就报错如下信息：IP地址冲突了

This subnet overlaps with another interface! 

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3. web截图报错信息