Fix control points with same timestamp potentially being parsed incorrectly

osu.Game/Beatmaps/ControlPoints/ControlPoint.cs

@@ -12,6 +12,11 @@ public class ControlPoint : IComparable<ControlPoint>, IEquatable<ControlPoint>
         /// </summary>
         public double Time;
 
+        /// <summary>
+        /// Whether this timing point was generated internally, as opposed to parsed from the underlying beatmap.
+        /// </summary>
+        internal bool AutoGenerated;
+
         public int CompareTo(ControlPoint other) => Time.CompareTo(other.Time);
 
         /// <summary>

osu.Game/Beatmaps/Formats/LegacyBeatmapDecoder.cs

@@ -374,14 +374,16 @@ private void handleTimingPoint(string line)
                 handleDifficultyControlPoint(new DifficultyControlPoint
                 {
                     Time = time,
-                    SpeedMultiplier = speedMultiplier
+                    SpeedMultiplier = speedMultiplier,
+                    AutoGenerated = timingChange
                 });
 
                 handleEffectControlPoint(new EffectControlPoint
                 {
                     Time = time,
                     KiaiMode = kiaiMode,
-                    OmitFirstBarLine = omitFirstBarSignature
+                    OmitFirstBarLine = omitFirstBarSignature,
+                    AutoGenerated = timingChange
                 });
 
                 handleSampleControlPoint(new LegacySampleControlPoint
@@ -389,7 +391,8 @@ private void handleTimingPoint(string line)
                     Time = time,
                     SampleBank = stringSampleSet,
                     SampleVolume = sampleVolume,
-                    CustomSampleBank = customSampleBank
+                    CustomSampleBank = customSampleBank,
+                    AutoGenerated = timingChange
                 });
             }
             catch (FormatException)
@@ -419,6 +422,11 @@ private void handleDifficultyControlPoint(DifficultyControlPoint newPoint)
             if (newPoint.EquivalentTo(existing))
                 return;
 
+            // autogenerated points should not replace non-autogenerated.
+            // this allows for incorrectly ordered timing points to still be correctly handled.
+            if (newPoint.AutoGenerated && !existing.AutoGenerated)
+                return;
+
             if (existing.Time == newPoint.Time)
                 beatmap.ControlPointInfo.DifficultyPoints.Remove(existing);