From 3ee6b8d2bcc5d12fc8a151e51aa5a345c950d043 Mon Sep 17 00:00:00 2001
From: metalgearsloth <31366439+metalgearsloth@users.noreply.github.com>
Date: Thu, 4 Jan 2024 15:04:43 +1100
Subject: [PATCH] Fix biome marker dupes (#23500)

---
 Content.Server/Parallax/BiomeSystem.cs | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/Content.Server/Parallax/BiomeSystem.cs b/Content.Server/Parallax/BiomeSystem.cs
index 09e202a76d..871373e9f8 100644
--- a/Content.Server/Parallax/BiomeSystem.cs
+++ b/Content.Server/Parallax/BiomeSystem.cs
@@ -631,8 +631,12 @@ public sealed partial class BiomeSystem : SharedBiomeSystem
                 }
 
                 DebugTools.Assert(layerProto.EntityMask.Count == 0 || !string.IsNullOrEmpty(proto));
+
+                // Don't fight other layers.
+                if (!spawnSet.TryAdd(node, proto))
+                    continue;
+
                 groupSize--;
-                spawnSet.Add(node, proto);
 
                 if (existing != null)
                 {