As more site owners have adopted AMP for speeding up mobile pages, measurement has lagged.
A visitor who went to an AMP-enabled page and a non-AMP page of a site was being counted as two separate people in Google Analytics.
In May, Google fixed the double-counting issue for visitors to publisher domain pages, but visitors to AMP Cache pages have still been counted separately in Analytics.
On Tuesday, Google announced a fix for AMP pages served via Google AMP Cache, including from Google search results.
Google’s new AMP Client ID API, coupled with Google Analytics, allows pages that are partially served on Google platforms like search and partially on site owner domains to communicate with each other.
Google Analytics “can understand if a user on your non-AMP pages had ever visited an AMP page displayed by Google.