Only substract $new_size_of_last_full once

zabbix_scripts/check_backuppc_sudo

@@ -83,7 +83,7 @@ if ( $host ) {
     $json->{new_size_q1}     = eval { int $sizes->quantile(1) } || 0;
     $json->{new_size_q3}     = eval { int $sizes->quantile(3) } || 0;
     $json->{enabled}         = ( $conf->{BackupsDisable} > 0 ) ? 0 : 1;
-    $json->{total_size}      = $sizes->sum + $json->{full_size} - 2 * $new_size_of_last_full;
+    $json->{total_size}      = $sizes->sum + $json->{full_size} - $new_size_of_last_full;
     $json->{history_size}    = $json->{total_size} - $json->{full_size};
     $json->{age}             = time - $bpc_info[$i]->{startTime};
 
@@ -149,8 +149,8 @@ if ( $host ) {
 
     # $json->{size} represents the total size used by this host.
     # But we want to substract the new size of the last full, as for this one we
-    # do not count sizeNew but size. As we've already added sizeNew we need to substract it 2 times
-    my $host_total_size = $host_new_size + $host_full_size - 2 * $host_new_size_of_last_full;
+    # do not count sizeNew but size
+    my $host_total_size = $host_new_size + $host_full_size - $host_new_size_of_last_full;
 
     # This one is kept just for compatibility. New Zabbix template will use total_size
     $json->{size}         += $host_total_size;