diff --git a/CHANGELOG.md b/CHANGELOG.md
index e0750f9a..eaef2bb0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -23,6 +23,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Use compact JSON for HTTP request/response body in debug log files. This makes logs much easier to
   scroll through.
 - Sonarr: Run version enforcement logic when using CFs instead of RPs.
+- A warning is now displayed when the same custom format is assigned multiple times to the same
+  quality profile.
 
 ## [2.5.0] - 2022-09-11
 
diff --git a/src/TrashLib/Services/CustomFormat/CustomFormatUpdater.cs b/src/TrashLib/Services/CustomFormat/CustomFormatUpdater.cs
index 2e0c973f..8d97e842 100644
--- a/src/TrashLib/Services/CustomFormat/CustomFormatUpdater.cs
+++ b/src/TrashLib/Services/CustomFormat/CustomFormatUpdater.cs
@@ -204,6 +204,25 @@ internal class CustomFormatUpdater : ICustomFormatUpdater
             _console.Output.WriteLine("");
         }
 
+        if (_guideProcessor.DuplicateScores.Any())
+        {
+            foreach (var (profileName, duplicates) in _guideProcessor.DuplicateScores)
+            foreach (var (trashId, dupeScores) in duplicates)
+            {
+                _log.Warning(
+                    "Custom format with trash ID {TrashId} is duplicated {Count} times in quality profile " +
+                    "{ProfileName} with the following scores: {Scores}",
+                    trashId, dupeScores.Count, profileName, dupeScores);
+            }
+
+            _log.Warning(
+                "When the same CF is specified multiple times with different scores in the same quality profile, " +
+                "only the score from the first occurrence is used. To resolve the duplication warnings above, " +
+                "remove the duplicate trash IDs from your YAML config");
+
+            _console.Output.WriteLine("");
+        }
+
         if (_guideProcessor.CustomFormatsWithOutdatedNames.Count > 0)
         {
             _log.Warning("One or more custom format names in your YAML config have been renamed in the guide and " +
diff --git a/src/TrashLib/Services/CustomFormat/Processors/GuideProcessor.cs b/src/TrashLib/Services/CustomFormat/Processors/GuideProcessor.cs
index f08d71e5..05e50336 100644
--- a/src/TrashLib/Services/CustomFormat/Processors/GuideProcessor.cs
+++ b/src/TrashLib/Services/CustomFormat/Processors/GuideProcessor.cs
@@ -40,6 +40,9 @@ internal class GuideProcessor : IGuideProcessor
     public IReadOnlyCollection<(string name, string trashId, string profileName)> CustomFormatsWithoutScore
         => _steps.QualityProfile.CustomFormatsWithoutScore;
 
+    public IReadOnlyDictionary<string, Dictionary<string, HashSet<int>>> DuplicateScores
+        => _steps.QualityProfile.DuplicateScores;
+
     public IReadOnlyCollection<TrashIdMapping> DeletedCustomFormatsInCache
         => _steps.CustomFormat.DeletedCustomFormatsInCache;
 
diff --git a/src/TrashLib/Services/CustomFormat/Processors/GuideSteps/IQualityProfileStep.cs b/src/TrashLib/Services/CustomFormat/Processors/GuideSteps/IQualityProfileStep.cs
index dfd9da1d..b3314f7e 100644
--- a/src/TrashLib/Services/CustomFormat/Processors/GuideSteps/IQualityProfileStep.cs
+++ b/src/TrashLib/Services/CustomFormat/Processors/GuideSteps/IQualityProfileStep.cs
@@ -6,5 +6,6 @@ public interface IQualityProfileStep
 {
     IDictionary<string, QualityProfileCustomFormatScoreMapping> ProfileScores { get; }
     IReadOnlyCollection<(string name, string trashId, string profileName)> CustomFormatsWithoutScore { get; }
+    IReadOnlyDictionary<string, Dictionary<string, HashSet<int>>> DuplicateScores { get; }
     void Process(IEnumerable<ProcessedConfigData> configData);
 }
diff --git a/src/TrashLib/Services/CustomFormat/Processors/GuideSteps/QualityProfileStep.cs b/src/TrashLib/Services/CustomFormat/Processors/GuideSteps/QualityProfileStep.cs
index f5931e50..bbbcdc4e 100644
--- a/src/TrashLib/Services/CustomFormat/Processors/GuideSteps/QualityProfileStep.cs
+++ b/src/TrashLib/Services/CustomFormat/Processors/GuideSteps/QualityProfileStep.cs
@@ -1,3 +1,4 @@
+using Common.Extensions;
 using TrashLib.Services.CustomFormat.Models;
 
 namespace TrashLib.Services.CustomFormat.Processors.GuideSteps;
@@ -6,12 +7,15 @@ internal class QualityProfileStep : IQualityProfileStep
 {
     private readonly Dictionary<string, QualityProfileCustomFormatScoreMapping> _profileScores = new();
     private readonly List<(string name, string trashId, string profileName)> _customFormatsWithoutScore = new();
+    private readonly Dictionary<string, Dictionary<string, HashSet<int>>> _duplicateScores = new();
 
     public IDictionary<string, QualityProfileCustomFormatScoreMapping> ProfileScores => _profileScores;
 
     public IReadOnlyCollection<(string name, string trashId, string profileName)> CustomFormatsWithoutScore
         => _customFormatsWithoutScore;
 
+    public IReadOnlyDictionary<string, Dictionary<string, HashSet<int>>> DuplicateScores => _duplicateScores;
+
     public void Process(IEnumerable<ProcessedConfigData> configData)
     {
         foreach (var config in configData)
@@ -46,6 +50,15 @@ internal class QualityProfileStep : IQualityProfileStep
                 ProfileScores[profile.Name] = mapping;
             }
 
+            // Check if this score was specified multiple times for the same profile. For each duplicate, we record
+            // the score of the second and onward occurrences for logging/reporting purposes.
+            var dupe = mapping.Mapping.FirstOrDefault(x => x.CustomFormat.TrashId.EqualsIgnoreCase(cf.TrashId));
+            if (dupe is not null)
+            {
+                _duplicateScores.GetOrCreate(profile.Name).GetOrCreate(cf.TrashId).Add(scoreToUse.Value);
+                continue;
+            }
+
             mapping.Mapping.Add(new FormatMappingEntry(cf, scoreToUse.Value));
         }
     }
diff --git a/src/TrashLib/Services/CustomFormat/Processors/IGuideProcessor.cs b/src/TrashLib/Services/CustomFormat/Processors/IGuideProcessor.cs
index b2380edd..78bd8988 100644
--- a/src/TrashLib/Services/CustomFormat/Processors/IGuideProcessor.cs
+++ b/src/TrashLib/Services/CustomFormat/Processors/IGuideProcessor.cs
@@ -15,6 +15,7 @@ internal interface IGuideProcessor
     IReadOnlyCollection<TrashIdMapping> DeletedCustomFormatsInCache { get; }
     IReadOnlyCollection<(string, string)> CustomFormatsWithOutdatedNames { get; }
     IDictionary<string, List<ProcessedCustomFormatData>> DuplicatedCustomFormats { get; }
+    IReadOnlyDictionary<string, Dictionary<string, HashSet<int>>> DuplicateScores { get; }
 
     Task BuildGuideDataAsync(IEnumerable<CustomFormatConfig> config, CustomFormatCache? cache,
         IGuideService guideService);