diff --git a/prototype/src/main/java/org/hso/ecommerce/controller/intern/InternArticleController.java b/prototype/src/main/java/org/hso/ecommerce/controller/intern/InternArticleController.java
index e6d6f52..57948a7 100644
--- a/prototype/src/main/java/org/hso/ecommerce/controller/intern/InternArticleController.java
+++ b/prototype/src/main/java/org/hso/ecommerce/controller/intern/InternArticleController.java
@@ -120,11 +120,17 @@ public class InternArticleController {
 	@PostMapping("/addArticle/{id}")
 	public RedirectView addArticle(@PathVariable(required = true) String id) {
 		// article is not already listed, create new one
-		int offeredArticleID = Integer.parseInt(id);
+		long offeredArticleID = Long.parseLong(id);
 
 		Article tmpArticle = new Article();
 
-		ArticleOffer offeredArticle = offersRepository.findOfferedArticleById(offeredArticleID);
+		ArticleOffer offeredArticle = offersRepository.findById(offeredArticleID).get();
+
+		// Check for duplicates
+		Optional<Article> related = articleRepository.findArticleByArticleOffer(offeredArticle);
+		if (related.isPresent()) {
+			return new RedirectView("../" + related.get().id);
+		}
 
 		// set default values
 		tmpArticle.description = "";