I don't understand your problem, so here's a WAG.

# require.one
sub foo { print "one\n" }
1;
[download]

# require.two
sub foo { print "two\n" }
1;
[download]

#!/usr/bin/perl

# https://perlmonks.org/?node_id=1218946

use strict;
use warnings;

require './require.one';

foo();

{ # lexical block
local *foo;
require './require.two';
foo();
} # end lexical block

foo();
[download]

"local" is your friend :)