How to: Create ONE applicaiton whith two activities, where one is started from account manager and the other started simpel

Hello.

I almost finished to allow my application being added as account-setting via the account-manager and AccountAuthorizer.
But until now I have TWO applications.
The one, which should create the account with user credentials and the other, which should use them and run with the credentials.

So, I would like to shrink those two applications into one.
Therefore I read about activities.
And there seems to that there is an approach where an application can determine, which activity should be started if there are more than one.
Something like activity Dummy starts, checks some stuff, and then decides, whether settings have to be called or a "real app".

But what I really would like to know is this:
How can I achieve, that my application starts my "settings-activity" if started from the account manager, BUT start the real application if started "not from the account manager". How to do that ?

Any help is appreciated.