1.8 URL structure & internationalisationHighVerified
Multiple URLs serving identical content
What it is
www/non-www, http/https, params all live.
Why it matters
Classic duplication splitting authority.
How to fix it
Choose a canonical form; redirect and canonicalise the rest.
Impact
Medium-high. Direct.
Evidence
Consolidate duplicate URLs to one canonical. Google Search Central, Consolidate duplicate URLs (canonicalization); Google Search Central, Keep a simple URL structure
Sources