diff --git a/back/src/Kyoo.Core/Controllers/ThumbnailsManager.cs b/back/src/Kyoo.Core/Controllers/ThumbnailsManager.cs
index 6e22c7dc..6e4720ce 100644
--- a/back/src/Kyoo.Core/Controllers/ThumbnailsManager.cs
+++ b/back/src/Kyoo.Core/Controllers/ThumbnailsManager.cs
@@ -17,17 +17,17 @@
 // along with Kyoo. If not, see <https://www.gnu.org/licenses/>.
 
 using System;
+using System.Collections.Generic;
 using System.IO;
 using System.Net.Http;
 using System.Threading.Tasks;
 using Blurhash.SkiaSharp;
 using Kyoo.Abstractions.Controllers;
 using Kyoo.Abstractions.Models;
+using Kyoo.Abstractions.Models.Exceptions;
 using Microsoft.Extensions.Logging;
 using SkiaSharp;
 
-#nullable enable
-
 namespace Kyoo.Core.Controllers
 {
 	/// <summary>
@@ -35,9 +35,8 @@ namespace Kyoo.Core.Controllers
 	/// </summary>
 	public class ThumbnailsManager : IThumbnailsManager
 	{
-		/// <summary>
-		/// A logger to report errors.
-		/// </summary>
+		private static readonly Dictionary<string, TaskCompletionSource<object>> _downloading = new();
+
 		private readonly ILogger<ThumbnailsManager> _logger;
 
 		private readonly IHttpClientFactory _clientFactory;
@@ -106,13 +105,49 @@ namespace Kyoo.Core.Controllers
 		public async Task DownloadImages<T>(T item)
 			where T : IThumbnails
 		{
-			if (item == null)
-				throw new ArgumentNullException(nameof(item));
-
 			string name = item is IResource res ? res.Slug : "???";
-			await _DownloadImage(item.Poster, _GetBaseImagePath(item, "poster"), $"The poster of {name}");
-			await _DownloadImage(item.Thumbnail, _GetBaseImagePath(item, "thumbnail"), $"The poster of {name}");
-			await _DownloadImage(item.Logo, _GetBaseImagePath(item, "logo"), $"The poster of {name}");
+
+			string posterPath = $"{_GetBaseImagePath(item, "poster")}.{ImageQuality.High.ToString().ToLowerInvariant()}.webp";
+			bool duplicated = false;
+			TaskCompletionSource<object>? sync = null;
+			try
+			{
+				lock (_downloading)
+				{
+					if (File.Exists(posterPath) || _downloading.ContainsKey(posterPath))
+					{
+						duplicated = true;
+						sync = _downloading.GetValueOrDefault(posterPath);
+					}
+					else
+					{
+						sync = new();
+						_downloading.Add(posterPath, sync);
+					}
+				}
+				if (duplicated)
+				{
+					object? dup = sync != null
+						? await sync.Task
+						: null;
+					throw new DuplicatedItemException(dup);
+				}
+
+				await _DownloadImage(item.Poster, _GetBaseImagePath(item, "poster"), $"The poster of {name}");
+				await _DownloadImage(item.Thumbnail, _GetBaseImagePath(item, "thumbnail"), $"The poster of {name}");
+				await _DownloadImage(item.Logo, _GetBaseImagePath(item, "logo"), $"The poster of {name}");
+			}
+			finally
+			{
+				if (!duplicated)
+				{
+					lock (_downloading)
+					{
+						_downloading.Remove(posterPath);
+						sync!.SetResult(item);
+					}
+				}
+			}
 		}
 
 		private static string _GetBaseImagePath<T>(T item, string image)
diff --git a/scanner/scanner/scanner.py b/scanner/scanner/scanner.py
index ad7432ae..c1823ac1 100644
--- a/scanner/scanner/scanner.py
+++ b/scanner/scanner/scanner.py
@@ -6,7 +6,7 @@ import re
 from aiohttp import ClientSession
 from pathlib import Path
 from guessit import guessit
-from typing import List, Literal
+from typing import List, Literal, Any
 from providers.provider import Provider
 from providers.types.collection import Collection
 from providers.types.episode import Episode, PartialShow
@@ -186,7 +186,7 @@ class Scanner:
 		)
 		return await self.post("seasons", data=season.to_kyoo())
 
-	async def post(self, path: str, *, data: object) -> str:
+	async def post(self, path: str, *, data: dict[str, Any]) -> str:
 		logging.debug(
 			"Sending %s: %s",
 			path,
@@ -206,19 +206,32 @@ class Scanner:
 				logging.error(f"Request error: {await r.text()}")
 				r.raise_for_status()
 			ret = await r.json()
+
+			if r.status == 409 and (
+				(path == "shows" and ret["startAir"][:4] != str(data["start_air"].year))
+				or (
+					path == "movies" and ret["airDate"][:4] != str(data["air_date"].year)
+				)
+			):
+				logging.info(
+					f"Found a {path} with the same slug ({ret['slug']}) and a different date, using the date as part of the slug"
+				)
+				year = (data["start_air"] if path == "movie" else data["air_date"]).year
+				data["slug"] = f"{ret['slug']}-{year}"
+				return await self.post(path, data=data)
 			return ret["id"]
 
 	async def delete(self, path: str):
 		logging.info("Deleting %s", path)
 		async with self._client.delete(
-			f"{self._url}/movies?path={path}", headers={"X-API-Key": self._api_key}
+			f"{self._url}/movies?filter=path eq \"{path}\"", headers={"X-API-Key": self._api_key}
 		) as r:
 			if not r.ok:
 				logging.error(f"Request error: {await r.text()}")
 				r.raise_for_status()
 
 		async with self._client.delete(
-			f"{self._url}/episodes?path={path}", headers={"X-API-Key": self._api_key}
+			f"{self._url}/episodes?filter=path eq \"{path}\"", headers={"X-API-Key": self._api_key}
 		) as r:
 			if not r.ok:
 				logging.error(f"Request error: {await r.text()}")