my @data = qw( 01 b2 01 00 b6 81 81 01 b4 0a 01 01 01 01
               00 01 00 00 01 00 c7 82 82 01 b2 01 00 b8 );

for ( 1 .. $#data ) {
    if ( $data[$_] =~ /(8[12])/ and $data[$_] eq $data[$_-1] ) {
        print "Match $1 ending at index $_\n";
    }
}