anchor.diff:       #{ timeout => 5000 },
        %% Run stage:
        begin
  -       {ok, SubscriberPid1} = start_subscriber(Config, [Topic1], InitArgs),
  -       {ok, SubscriberPid2} = start_subscriber(Config, [Topic2], InitArgs),
  +       {ok, SubscriberPid1} = start_subscriber(?group_id, Config, [Topic1], InitArgs),
  +       {ok, SubscriberPid2} = start_subscriber(?group_id, Config, [Topic2], InitArgs),
          %% Send messages to random partitions:
          lists:foreach(SendFun, L),
          ?wait_message(_, _, LastMsg, _)
  
positive.code:      #{ timeout => 5000 },
       %% Run stage:
       begin
         {ok, SubscriberPid} = start_subscriber(Config, [Topic], InitArgs),
         %% Send a message to the topic and wait until it's received to make sure the subscriber is stable:
         produce({Topic, Partition}, <<0>>),
         {ok, _} = ?wait_message(Topic, Partition, <<0>>, _),
  
negative.code:        %% Send messages:
         {LastOffset, L} = produce_payloads(Topic, 0, Config),
         %% Start two subscribers competing for the partition:
         {ok, SubscriberPid1} = start_subscriber(?group_id, Config, [Topic], InitArgs),
         {ok, SubscriberPid2} = start_subscriber(?group_id, Config, [Topic], InitArgs),
         ?wait_message(_, _, _, LastOffset),
         L
       end,
  