A Schema.org object of type Person can have a sameAs property of type URL. According to Google's structured data site, the sameAs property can be a single item or an array.
The docs on Schema.org do not mention whether sameAs can be a single item or an array. Is this just Google deviating from Schema.org? Or is it the case that all properties in Schema.org can be single items or arrays?
Every Schema.org property can have multiple values. It doesn’t necessarily make sense for some properties (e.g., birthDate), but it’s still allowed.
In JSON-LD:
"sameAs": ["/foo", "/bar"],
In Microdata:
<link itemprop="sameAs" href="/foo" />
<link itemprop="sameAs" href="/bar" />
In RDFa:
<link property="sameAs" href="/foo" />
<link property="sameAs" href="/bar" />
This doesn’t necessarily mean that Google (or any other consumer) supports this for every property, too. So when Google explicitly mentions this in their documentation, you can be sure that the respective search result feature works with multiple values.