[Push] one or many

I'm really confused by what seems to me like contradictory prose... In
the interface definition it says

"""
Note that just a single push registration is allowed per webapp.
"""

But in multiple places it seems to suggest otherwise, for example, in
the section on uniqueness it says:

"""
webapps that create multiple push registrations are responsible for
mapping the individual registrations to specific app functions as
neces
""

Can someone clarify why those seem contradictory?  Can a webapp have 1
registration, or many?

-Brian