Fixed: Avoid failure if list contains same movie but without tmdbid

Fixes #7454

src/NzbDrone.Core/ImportLists/FetchAndParseImportListService.cs

@@ -167,6 +167,7 @@ private List<ImportListMovie> MapMovieReports(List<ImportListMovie> reports)
         {
             var mappedMovies = reports.Select(m => _movieSearch.MapMovieToTmdbMovie(new MovieMetadata { Title = m.Title, TmdbId = m.TmdbId, ImdbId = m.ImdbId, Year = m.Year }))
                                       .Where(x => x != null)
+                                      .DistinctBy(x => x.TmdbId)
                                       .ToList();
 
             _movieMetadataService.UpsertMany(mappedMovies);