Well... once you know which they are, I guess not (or that's another problem), but it is important to correctly define what are 'yesterday files'.

I think it would be not an decision based on file_age_in_days, but rather something like 'those files that have creation date between yesterday 00:00:00 and today 00:00:00'.

Something like below:

use strict;
use warnings;

use Date::Manip;
use File::stat;

my $yesterday = ParseDate( 'yesterday midnight' );
my $today     = ParseDate( 'today midnight' );

my $yesterday_midnight = &UnixDate( $yesterday, "%s" );
my $today_midnight     = &UnixDate( $today, "%s" );

my @yesterday_files = ();

foreach my $file ( <*> ) {
    my $stat = stat( $file )
        or die "Cannot stat file $file: $!\n";

    my $creation_date = $stat->ctime;

    push( @yesterday_files, $file )
        if (    $creation_date < $today_midnight
            and $creation_date > $yesterday_midnight );
}

foreach my $file (@yesterday_files) {
     # process, copy, ...
}
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