How do I deduplicate URLs across multiple sitemaps?

When merging multiple sitemaps (or following a sitemap-index), the same URL can legitimately appear in more than one child sitemap — typically when a site splits sitemaps by content type but a URL belongs to two types. xmlsitemapmaker.com deduplicates by URL string on every conversion, so you never see duplicates in the output. If you're doing it yourself in Excel: Data → Remove Duplicates → check only the URL column. In Python: pass the URL list through dict.fromkeys(urls) or a set to dedupe while preserving order. Be careful with URLs that differ only by trailing slash or fragment — decide whether those should be treated as duplicates before deduplication, because most tools treat them as distinct.