BEGIN{
    # load Pack1 defining "package Abc;"
    require Pack1;

    # copy the Abc namespace to Cde namespace
    my $ref = $main::{'Abc::'};
    foreach my $n (keys %$ref)
    {
        *{"Cde::$n"} = $ref->{$n};
    }

    # remove Abc namespace
    delete $main::{'Abc::'};
}

BEGIN
{
# load Pack2 also defining "package Abc;"
require Pack2;
}

# now the first version is in Cde package,
# the second version is in Abc package
Cde::test();
Abc::test();