Two Hostnames with the same IP Address

Kevin Lovegrove I already done all this

Please see below when i ping the 2 different hosts 

ping rawabi413.ddns.cyberoam.com

Pinging rawabi413.ddns.cyberoam.com [192.168.20.18] with 32 bytes of data:
Reply from 192.168.20.18: bytes=32 time=1ms TTL=64
Reply from 192.168.20.18: bytes=32 time<1ms TTL=64
Reply from 192.168.20.18: bytes=32 time=1ms TTL=64
Reply from 192.168.20.18: bytes=32 time<1ms TTL=64

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ping mikrotikpambosoffice

Pinging mikrotikpambosoffice.monarchgroup.local [192.168.20.18] with 32 bytes of data:
Reply from 192.168.20.18: bytes=32 time<1ms TTL=64
Reply from 192.168.20.18: bytes=32 time<1ms TTL=64
Reply from 192.168.20.18: bytes=32 time<1ms TTL=64
Reply from 192.168.20.18: bytes=32 time<1ms TTL=64

You see the problem. I need the rawabi413.ddns.cyberoam.com to be deleted from my DNS

Any Suggestions: