I did more reading in Android Docs — I could spend a lifetime reading their docs and find a new subtle detail that breaks my brain 🙂 This explains my multiple-instances that I did not expect, however, I configured to occur.
Android Doc on Activity definition for AndroidManifest.xml
The “standard” and “singleTop” modes
differ from each other in just one
respect: Every time there’s new intent
for a “standard” activity, a new
instance of the class is created to
respond to that intent. Each instance
handles a single intent. Similarly, a
new instance of a “singleTop” activity
may also be created to handle a new
intent. However, if the target task
already has an existing instance of
the activity at the top of its stack,
that instance will receive the new
intent (in an onNewIntent() call); a
new instance is not created. In other
circumstances — for example, if an
existing instance of the “singleTop”
activity is in the target task, but
not at the top of the stack, or if
it’s at the top of a stack, but not in
the target task — a new instance would
be created and pushed on the stack.