use strict;
use warnings;
use Data::Dumper;

my $text = "foo##loop nase## foo  ##if nase-kz_gesetzt## foo\n##loop nase##foo ##if nase-kz_gesetzt##foo";

my @foo = split /(##.+?##)/, $text;
my @bar = split /##(.+?)##/, $text;
my @foobar = ($text =~ /##(.+?)##/g);

chomp(@foo,@bar,@foobar);

print Dumper(\@foo);
print Dumper(\@bar);
print Dumper(\@foobar);