avoid duplicates in split view

immichFrame.Web/src/lib/components/home-page/home-page.svelte

@@ -180,7 +180,10 @@
 		}
 
 		const useSplit = shouldUseSplitView(assetBacklog);
-		const next = assetBacklog.splice(0, useSplit ? 2 : 1);
+		let next = assetBacklog.splice(0, useSplit ? 2 : 1);
+
+		next = removeDuplicateFromNextAssets(next);
+
 		assetBacklog = [...assetBacklog];
 
 		if (displayingAssets.length) {
@@ -196,6 +199,40 @@
 		assetsState = await pickAssets(next);
 	}
 
+	function removeDuplicateFromNextAssets(next: api.AssetResponseDto[]): api.AssetResponseDto[]{
+		if(isDuplicate(next)){
+			const nextPortrait = tryPopNextNonDuplicatePortraitInBacklog([next[0]]);
+			let result = [next[0]];
+			if(nextPortrait !== undefined) {
+				result.push(nextPortrait);
+			} 
+			return result;
+		}
+		return next;
+	}
+
+	function isDuplicate(next: api.AssetResponseDto[]): boolean{
+		const seen = new Set<string>();
+
+		for(const item of next){
+			if(seen.has(item.id)){
+				return true;
+			}
+			seen.add(item.id);
+		}
+		return false;
+	}
+
+	function tryPopNextNonDuplicatePortraitInBacklog(next: api.AssetResponseDto[]): api.AssetResponseDto | undefined{
+		for(let i = 0; i < assetBacklog.length; i++){
+			const backlogAsset = assetBacklog[i];
+			if(!isPortrait(backlogAsset)) continue;
+			if(isDuplicate([...next, backlogAsset])) continue;
+			return assetBacklog.splice(i, 1)[0];
+		}
+		return undefined;
+	}
+
 	async function getPreviousAssets() {
 		if (!assetHistory.length) {
 			return;