diff --git a/lib/Controller/findMementos.php b/lib/Controller/findMementos.php
index fcdef39..c71aee0 100644
--- a/lib/Controller/findMementos.php
+++ b/lib/Controller/findMementos.php
@@ -25,13 +25,10 @@ trait MementoFinder {
 		if ($this->loggedInUserId === $userId) {
 			$userFolder = $this->serverContainer->getUserFolder($this->loggedInUserId);
 			$moreMementos = findPrivateMementos($userFolder);
-			$foundMementos = mergeMementos($foundMementos, $moreMementos);
+			$foundMementos = array_merge($foundMementos, $moreMementos);
 		}
 
-		// Filter those that match the requested URL, and sort them.
-		$matchingMementos = filterMementosByUrl($foundMementos, $url);
-		sortMementos($matchingMementos);
-		return $matchingMementos;
+		return listMementosMatchingUrl($foundMementos, $url);
 	}
 
 	function findAllUsersMementosForUrl($url) {
@@ -45,20 +42,17 @@ trait MementoFinder {
 		$shareManager = $this->serverContainer->getShareManager();
 		foreach ($allUserIds as $userId) {
 			$moreMementos = findPublicMementos($shareManager, $userId);
-			$foundMementos = mergeMementos($foundMementos, $moreMementos);
+			$foundMementos = array_merge($foundMementos, $moreMementos);
 		}
 
 		// If logged in, get current user's private mementos too.
 		if ($this->loggedInUserId) {
 			$userFolder = $this->serverContainer->getUserFolder($this->loggedInUserId);
 			$moreMementos = findPrivateMementos($userFolder);
-			$foundMementos = mergeMementos($foundMementos, $moreMementos);
+			$foundMementos = array_merge($foundMementos, $moreMementos);
 		}
 
-		// Filter those that match the requested URL, and sort them.
-		$matchingMementos = filterMementosByUrl($foundMementos, $url);
-		$matchingMementos = sortMementos($matchingMementos);
-		return $matchingMementos;
+		return listMementosMatchingUrl($foundMementos, $url);
 	}
 }
 
@@ -127,9 +121,14 @@ function findPublicMementos($shareManager, $userId) {
 	return $foundMementos;
 }
 
-function mergeMementos($mementos1, $mementos2) {
-	// TODO deduplicate (we'll get public & private URLs for the same files)
-	return array_merge($mementos1, $mementos2);
+function listMementosMatchingUrl($foundMementos, $url) {
+	// Filter those that match the requested URL
+	$matchingMementos = filterMementosByUrl($foundMementos, $url);
+	// Deduplicate (as a file may be accessible both through a public and a private URL)
+	$matchingMementos = deduplicateMementos($matchingMementos);
+	// Sort them by date.
+	$matchingMementos = sortMementos($matchingMementos);
+	return $matchingMementos;
 }
 
 function filterMementosByUrl($mementos, $url) {
@@ -155,6 +154,18 @@ function normaliseUrl($url) {
 	return $url;
 }
 
+function deduplicateMementos($mementos) {
+	$deduped = [];
+	$seenIds = [];
+	foreach ($mementos as $memento) {
+		if (!array_key_exists($memento['id'], $seenIds)) {
+			$deduped[] = $memento;
+			$seenIds[$memento['id']] = null;
+		}
+	}
+	return $deduped;
+}
+
 // Sort an array of mementos by their datetime. Oldest first.
 function sortMementos($mementos) {
 	usort($mementos, function ($m1, $m2) { return $m1['datetime'] <=> $m2['datetime']; });
@@ -177,7 +188,8 @@ function extractMementoInfo($file) {
 	$datetime = getDatetime($headElement);
 	return [
 		'originalUrls' => $originalUrls,
-		'datetime' => $datetime
+		'datetime' => $datetime,
+		'id' => $file->getFileInfo()->getId() // for deduplication
 	];
 }