@tapes_for_box1 = @unique_vault_list[0..19];
@tapes_for_box2 = @unique_vault_list[20..$#unique_vault_list];

##</code><code>##

@tapes_for_box1 = splice(@unique_vault_list, 0, 20);
@tapes_for_box2 = @unique_vault_list;

##</code><code>##

my @tapes_by_box;
push(@tapes_by_box, [ splice(@unique_vault_list, 0, 20) ])
   while @unique_vault_list;