#!/usr/bin/perl

use strict;
use warnings;

my %all = map{$_, $_} do{local @ARGV = shift; <>};

%all = map{$_, $_} grep defined, @all{do{local @ARGV = $_; <>}} for @A
+RGV;

print sort keys %all;
[download]

Outputs:

ID121 ABC14
ID122 EFG87
ID157 TSR11
[download]

which looks right.

Hash slices can be your friend :)