Our existing policy has required each sitelink in a campaign to link to a different landing page. That means a user would have a meaningfully different experience on the landing page from each sitelink. Recently, though, we've noticed an increase in the number of sitelinks created with the same landing page URLs or identical content. So starting today, we are beginning more proactive enforcement of our policy. Google AdWords Unique Sitelinks Policy To Be Proactively Enforced [adwords.blogspot.co.uk]
We’ll initially focus on new sitelinks and any sitelinks that you change. As your ads are being served, our systems will verify that your sitelinks meet the policy standards. Sitelinks that don’t meet the standards will be restricted from appearing.
We realize that manually checking and fixing duplicates among your existing sitelinks and landing pages might take some time. So we’re delaying proactive enforcement with existing sitelinks for a few months.