Fixed: Do not replace a file unless it contains the same episodes

src/NzbDrone.Core/DecisionEngine/SameEpisodesSpecification.cs

@@ -0,0 +1,35 @@
+using System.Collections.Generic;
+using System.Linq;
+using NzbDrone.Common.Extensions;
+using NzbDrone.Core.Tv;
+
+namespace NzbDrone.Core.DecisionEngine
+{
+    public class SameEpisodesSpecification
+    {
+        private readonly IEpisodeService _episodeService;
+
+        public SameEpisodesSpecification(IEpisodeService episodeService)
+        {
+            _episodeService = episodeService;
+        }
+
+        public bool IsSatisfiedBy(List<Episode> episodes)
+        {
+            var episodeIds = episodes.SelectList(e => e.Id);
+            var episodeFileIds = episodes.Where(c => c.EpisodeFileId != 0).Select(c => c.EpisodeFileId).Distinct();
+
+            foreach (var episodeFileId in episodeFileIds)
+            {
+                var episodesInFile = _episodeService.GetEpisodesByFileId(episodeFileId);
+
+                if (episodesInFile.Select(e => e.Id).Except(episodeIds).Any())
+                {
+                    return false;
+                }
+            }
+
+            return true;
+        }
+    }
+}