What does the Also Published As field indicate on Google patents? For example, for a single European patent application, there are multiple US patents listed under this field.
The "Also Published As" field on Google Patents relates to patent families - i.e. patent documents that share a priority number and an associated priority date.
There are several different ways to define a patent family, depending on how documents with multiple priority numbers are treated (see http://www.epo.org/searching/essentials/patent-families/definitions.html). I am not sure which method Google uses.
Essentially, it means that those documents are related. It may be the application and grant within a particular country, or the corresponding documents for the same invention in different countries.