diff --git a/backend/src/main/java/com/vaessl/app/connection/ConnectionEntity.java b/backend/src/main/java/com/vaessl/app/connection/ConnectionEntity.java
index df06a47..96b769f 100644
--- a/backend/src/main/java/com/vaessl/app/connection/ConnectionEntity.java
+++ b/backend/src/main/java/com/vaessl/app/connection/ConnectionEntity.java
@@ -8,12 +8,13 @@ import jakarta.persistence.Id;
 import jakarta.persistence.Inheritance;
 import jakarta.persistence.InheritanceType;
 import jakarta.persistence.Table;
+import jakarta.persistence.UniqueConstraint;
 import lombok.Getter;
 import lombok.NoArgsConstructor;
 import lombok.Setter;
 
 @Entity
-@Table(name = "connections")
+@Table(name = "connections", uniqueConstraints = { @UniqueConstraint(columnNames = { "appUrl", "username" }) })
 @Inheritance(strategy = InheritanceType.SINGLE_TABLE)
 @DiscriminatorColumn(name = "service_type")
 @Getter
@@ -23,6 +24,7 @@ public abstract class ConnectionEntity {
     @Id
     @GeneratedValue(strategy = GenerationType.IDENTITY)
     private Long id;
-    
+
     private String appUrl;
+    private String username;
 }
diff --git a/backend/src/main/java/com/vaessl/app/connection/ConnectionProvider.java b/backend/src/main/java/com/vaessl/app/connection/ConnectionProvider.java
index ac05ca7..0b6e893 100644
--- a/backend/src/main/java/com/vaessl/app/connection/ConnectionProvider.java
+++ b/backend/src/main/java/com/vaessl/app/connection/ConnectionProvider.java
@@ -9,6 +9,8 @@ public interface ConnectionProvider {
 
     ConnectionResponse authenticate(ConnectionRequest request);
 
+    ConnectionEntity findUniqueConnectionEntry(ConnectionRequest request);
+
     ConnectionEntity connectionToEntity(ConnectionRequest request, ConnectionResponse response);
 
     void updateToRepository(ConnectionEntity existing, ConnectionResponse response);
diff --git a/backend/src/main/java/com/vaessl/app/connection/ConnectionRepository.java b/backend/src/main/java/com/vaessl/app/connection/ConnectionRepository.java
index d02823b..880f567 100644
--- a/backend/src/main/java/com/vaessl/app/connection/ConnectionRepository.java
+++ b/backend/src/main/java/com/vaessl/app/connection/ConnectionRepository.java
@@ -6,5 +6,5 @@ import org.springframework.stereotype.Repository;
 @Repository
 public interface ConnectionRepository extends JpaRepository<ConnectionEntity, Long> {
 
-    ConnectionEntity findByAppUrl(String appUrl);
+    ConnectionEntity findByAppUrlAndUsername(String appUrl, String username);
 }
diff --git a/backend/src/main/java/com/vaessl/app/connection/ConnectionService.java b/backend/src/main/java/com/vaessl/app/connection/ConnectionService.java
index ea5a526..86c3b28 100644
--- a/backend/src/main/java/com/vaessl/app/connection/ConnectionService.java
+++ b/backend/src/main/java/com/vaessl/app/connection/ConnectionService.java
@@ -33,7 +33,7 @@ public class ConnectionService {
 
         ConnectionResponse response = provider.authenticate(request);
 
-        ConnectionEntity existing = cRepository.findByAppUrl(request.appUrl());
+        ConnectionEntity existing = provider.findUniqueConnectionEntry(request);
 
         if (existing != null) {
             provider.updateToRepository(existing, response);
diff --git a/backend/src/main/java/com/vaessl/app/connection/HomeBoxConnectionProvider.java b/backend/src/main/java/com/vaessl/app/connection/HomeBoxConnectionProvider.java
index 3294cd7..c8fc2d3 100644
--- a/backend/src/main/java/com/vaessl/app/connection/HomeBoxConnectionProvider.java
+++ b/backend/src/main/java/com/vaessl/app/connection/HomeBoxConnectionProvider.java
@@ -54,6 +54,12 @@ public class HomeBoxConnectionProvider implements ConnectionProvider {
         return new ConnectionResponse(hbResponse.token(), hbResponse.expiresAt(), attachmentToken);
     }
 
+    @Override
+    public ConnectionEntity findUniqueConnectionEntry(ConnectionRequest request) {
+
+        return cRepository.findByAppUrlAndUsername(request.appUrl(), request.credentials().get("username"));
+    }
+
     @Override
     public ConnectionEntity connectionToEntity(ConnectionRequest request, ConnectionResponse response) {
         return HomeboxEntity.from(request, response);
diff --git a/backend/src/main/java/com/vaessl/app/connection/HomeboxEntity.java b/backend/src/main/java/com/vaessl/app/connection/HomeboxEntity.java
index f23521d..c134af0 100644
--- a/backend/src/main/java/com/vaessl/app/connection/HomeboxEntity.java
+++ b/backend/src/main/java/com/vaessl/app/connection/HomeboxEntity.java
@@ -25,6 +25,7 @@ public class HomeboxEntity extends ConnectionEntity {
         HomeboxEntity he = new HomeboxEntity();
 
         he.setAppUrl(request.appUrl());
+        he.setUsername(request.credentials().get("username"));
         he.setToken(response.token());
         he.setAttachmentToken(response.getExtraVar("attachmentToken"));
         he.setExpiresAt(response.expiresAt());
diff --git a/backend/src/test/java/com/vaessl/app/connection/HomeboxIntegrationTest.java b/backend/src/test/java/com/vaessl/app/connection/HomeboxIntegrationTest.java
index 2f7cf3c..4ea7388 100644
--- a/backend/src/test/java/com/vaessl/app/connection/HomeboxIntegrationTest.java
+++ b/backend/src/test/java/com/vaessl/app/connection/HomeboxIntegrationTest.java
@@ -179,11 +179,12 @@ class HomeboxIntegrationTest {
 
         DocumentContext responseContext = JsonPath.parse(response.getBody());
 
-        ConnectionEntity dbEntry = cRepository.findByAppUrl(request.appUrl());
+        ConnectionEntity dbEntry = cRepository.findByAppUrlAndUsername(request.appUrl(), request.credentials().get("username"));
 
         assertThat(dbEntry).isNotNull();
 
         assertThat(dbEntry.getAppUrl()).isEqualTo(request.appUrl());
+        assertThat(dbEntry.getUsername()).isEqualTo(request.credentials().get("username"));
 
         if (dbEntry instanceof HomeboxEntity hbE) {
             assertThat(hbE.getToken()).isEqualTo(responseContext.read("$.token"));