diff --git a/lib/Ravada/Request.pm b/lib/Ravada/Request.pm
index 60fe69dcf..8f92fe5f8 100644
--- a/lib/Ravada/Request.pm
+++ b/lib/Ravada/Request.pm
@@ -713,6 +713,7 @@ sub _duplicated_request($self=undef, $command=undef, $args=undef) {
     confess "Error: missing command " if !$command;
     #    delete $args_d->{uid} unless $command eq 'clone';
     delete $args_d->{uid} if $command =~ /(cleanup|refresh_vms|set_base_vm)/;
+    delete $args_d->{uid} if exists $args_d->{uid} && !defined $args_d->{uid};
     delete $args_d->{at};
     delete $args_d->{status};
     delete $args_d->{timeout};
@@ -720,7 +721,7 @@ sub _duplicated_request($self=undef, $command=undef, $args=undef) {
     my $sth = $$CONNECTOR->dbh->prepare(
         "SELECT id,args FROM requests WHERE (status <> 'done')"
         ." AND command=?"
-        ." AND ( error = '' OR error is NULL)"
+        ." AND ( error = '' OR error is NULL OR error like '% waiting for process%')"
     );
     $sth->execute($command);
     while (my ($id,$args_found) = $sth->fetchrow) {
diff --git a/script/rvd_back b/script/rvd_back
index 3b7ca9c2f..a17e82849 100755
--- a/script/rvd_back
+++ b/script/rvd_back
@@ -280,9 +280,12 @@ sub do_start {
 
         if ( time - $t_refresh > 60 ) {
             Ravada::Request->cleanup();
-            Ravada::Request->refresh_vms()      if rand(5)<3;
-            Ravada::Request->enforce_limits()   if rand(5)<2;
-            Ravada::Request->manage_pools()     if rand(5)<2;
+            next if rand(5)>2;
+
+            Ravada::Request->refresh_vms();
+            Ravada::Request->enforce_limits();
+            Ravada::Request->manage_pools();
+
             $t_refresh = time;
         }
         sleep 1 if time - $t0 <1;