diff --git a/lib/private/OCM/Model/OCMProvider.php b/lib/private/OCM/Model/OCMProvider.php
index 6c1591013a7a3..899cb73aea415 100644
--- a/lib/private/OCM/Model/OCMProvider.php
+++ b/lib/private/OCM/Model/OCMProvider.php
@@ -179,6 +179,21 @@ public function createNewResourceType(): IOCMResource {
 	 */
 	#[\Override]
 	public function addResourceType(IOCMResource $resource): static {
+		foreach ($this->resourceTypes as $existing) {
+			if ($existing->getName() === $resource->getName()) {
+				$existing->setShareTypes(array_values(array_unique(
+					array_merge(
+						$existing->getShareTypes(),
+						$resource->getShareTypes()
+					)
+				)));
+				$existing->setProtocols(array_merge(
+					$existing->getProtocols(),
+					$resource->getProtocols()
+				));
+				return $this;
+			}
+		}
 		$this->resourceTypes[] = $resource;
 
 		return $this;
diff --git a/tests/lib/OCM/OCMProviderTest.php b/tests/lib/OCM/OCMProviderTest.php
new file mode 100644
index 0000000000000..bae2abef9a8b4
--- /dev/null
+++ b/tests/lib/OCM/OCMProviderTest.php
@@ -0,0 +1,72 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2026 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace Test\OCM;
+
+use OC\OCM\Model\OCMProvider;
+use OCP\OCM\IOCMResource;
+use Test\TestCase;
+
+class OCMProviderTest extends TestCase {
+	private OCMProvider $provider;
+
+	#[\Override]
+	protected function setUp(): void {
+		parent::setUp();
+		$this->provider = new OCMProvider();
+	}
+
+	private function resource(string $name, array $shareTypes, array $protocols): IOCMResource {
+		$resource = $this->provider->createNewResourceType();
+		$resource->setName($name)
+			->setShareTypes($shareTypes)
+			->setProtocols($protocols);
+		return $resource;
+	}
+
+	public function testAddResourceTypeKeepsDistinctNames(): void {
+		$this->provider->addResourceType($this->resource('file', ['user'], ['webdav' => '/dav/']));
+		$this->provider->addResourceType($this->resource('folder', ['user'], ['webapp' => []]));
+
+		$this->assertCount(2, $this->provider->getResourceTypes());
+	}
+
+	public function testAddResourceTypeMergesSameName(): void {
+		$this->provider->addResourceType($this->resource('folder', ['user'], ['webapp' => []]));
+		$this->provider->addResourceType($this->resource('folder', ['user'], ['webapp-receive' => ['targets' => ['blank', 'iframe']]]));
+
+		$resourceTypes = $this->provider->getResourceTypes();
+		$this->assertCount(1, $resourceTypes);
+		$this->assertSame(
+			['webapp' => [], 'webapp-receive' => ['targets' => ['blank', 'iframe']]],
+			$resourceTypes[0]->getProtocols(),
+		);
+	}
+
+	public function testAddResourceTypeDedupesShareTypes(): void {
+		$this->provider->addResourceType($this->resource('folder', ['user'], ['webapp' => []]));
+		$this->provider->addResourceType($this->resource('folder', ['user', 'group'], ['webapp-receive' => []]));
+
+		$shareTypes = $this->provider->getResourceTypes()[0]->getShareTypes();
+		$this->assertSame(['user', 'group'], $shareTypes);
+		// Deduplication must not leave key gaps, or shareTypes would
+		// serialize as a JSON object instead of an array.
+		$this->assertSame('["user","group"]', json_encode($shareTypes));
+	}
+
+	public function testAddResourceTypeMergeOverwritesSameProtocol(): void {
+		$this->provider->addResourceType($this->resource('folder', ['user'], ['webapp' => ['a' => 1]]));
+		$this->provider->addResourceType($this->resource('folder', ['user'], ['webapp' => ['b' => 2]]));
+
+		$this->assertSame(
+			['webapp' => ['b' => 2]],
+			$this->provider->getResourceTypes()[0]->getProtocols(),
+		);
+	}
+}