opendir(DIR,$somepath);
my %todelete;
while( $file = grep /[^.]/, readdir DIR ) {
    if ( !exists( $todelete{$file} ) and some_test( "$somepath/$file" )) {
        $todelete{$file} = undef;
        ( my $otherfile = $file ) =~ s/this/that/;
        $todelete{$otherfile} = undef;
    }
}
unlink "$somepath/$_" for ( keys %todelete );