File::Find changes the cwd, so you'll need to cache that using Cwd in order to avoid trying to copy a file over itself

#!/usr/bin/perl -w 
use strict;  
use warnings; 

use Cwd qw(getcwd);
use File::Copy;
use File::Find;

my $dir = shift;
print "$dir\n";

my $cwd = getcwd;

my %files = map {$_ => 1} qw(data.txt datascript.pl);

find(sub {
    copy($File::Find::name, $cwd) or die "Can't cp $File::Find::name: 
+$!"
        if (delete $files{$_});
}, $dir);
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