#!/usr/bin/perl

# http://perlmonks.org/?node_id=1190966

use strict;
use warnings;

$_ = do { local $/; <DATA> };

s/^(\w+(?:[-_]\d+)?)\n(?=.*\1\b)//gm;

print;

__DATA__
Text_1
sample-text file Text_1
 matching the 1st line
 matching the last line
Text
text_1
text-2
sample-text file text-2
 matching the 1st line
 matching the last line
text_1
text-2
text
sample-text file text
 matching the 1st line
 matching the last line