#!/usr/local/bin/perl -w

use strict;
use Data::Dumper;

undef $/;
my %t = <DATA> =~ /(\w{2})\s+((?:.+\n)(?:\s{2}.+\n)*)/g;
grep { $t{$_} = [split /\n\s*/, $t{$_}]; } keys %t;
print Dumper(\%t);

__DATA__
T1 Line1
T2 Line2
   Line3
   Line4
T3 Line5
   Line6
ER