If you try to sort them with sort -u, then you'll have problems. For example, '10' will get placed before '5'.

not necessarily true...

$ cat sorttest 
10.1.1.2
100.1.3.2
10.20.3.2
10.2.4.3
5.4.3.2
5.10.3.2
5.5.3.2

$ sort -t . -k 1,1n -k 2,2n -k 3,3n -k 4,4n sorttest 
5.4.3.2
5.5.3.2
5.10.3.2
10.1.1.2
10.2.4.3
10.20.3.2
100.1.3.2
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