@cadusilva solução tosca, mas que aparentemente resolve (em Python):
```
import re
ips = {}
with open("ip_list_file", "r") as ip_list:
for ip in ip_list:
base_ip = ip[0:15]
if base_ip not in ips:
ips[base_ip] = ip.strip()
else:
if re.search(r"\d{3}\.\d{3}\.\d{3}\.\d{3}\/\d{2}", ip.strip()):
ips[base_ip] = ip.strip()
print(list(ips.values()))
```