Assuming "repeated number groups" rather than pairs, and without modules so you can see the logic:

#! perl -slw
use strict;
use Data::Dump qw[ pp ];

my %dups;

while( <DATA> ) {
    my @nums = split ' ', $_;
    for my $l ( 2 .. @nums ) {
        ++$dups{ join ' ', @nums[ $_ .. $_+$l-1 ] } for 0 .. @nums - $
+l;
    }
}
#pp \%dups;

$dups{ $_ } > 1 and print "$dups{ $_ } x '$_'" for sort keys %dups;

__DATA__
1 2 5 9
1 2 5 10
4 5 10 12
5 9 10 11
[download]

Produces:

C:\test>1218823.pl
2 x '1 2'
2 x '1 2 5'
2 x '2 5'
2 x '5 10'
2 x '5 9'
[download]