cat perlout.txt | sort | uniq
192.168.1.1
192.168.1.188
fdba:7b43:1916::1
fdba:7b43:1916::d34
fe80::eade:27ff:feb6:fa8c
fe80::ec78:4ff:fec0:a17b

cat perlout.txt | sort | uniq -u
192.168.1.188
fdba:7b43:1916::1
fe80::eade:27ff:feb6:fa8c
fe80::ec78:4ff:fec0:a17b

When pre-filter one more time with uniq, then they give same result
cat perlout.txt | sort | uniq | uniq
192.168.1.1
192.168.1.188
fdba:7b43:1916::1
fdba:7b43:1916::d34
fe80::eade:27ff:feb6:fa8c
fe80::ec78:4ff:fec0:a17b

cat perlout.txt  | sort | uniq | uniq -u
192.168.1.1
192.168.1.188
fdba:7b43:1916::1
fdba:7b43:1916::d34
fe80::eade:27ff:feb6:fa8c
fe80::ec78:4ff:fec0:a17b