use Data::Dump qw[ pp ];

my @v = ([100, 200],[200, 300],[200, 100]);;

my %uniq; 
my @r = grep{ 
    ++$uniq{ join $;, $_->[0], $_->[1] } == 1 
    and 
    ++$uniq{ join $;, $_->[1], $_->[0] } == 1 
} @v;;

pp @r;;
([100, 200], [200, 300])