It is an already known issue of the tool (I suppose you are using eclipse). Google Group - Android Developers.
The Application and the first Activity share the same name specified in the android:label field of the <activity> item.
If you want to use different titles for the launcher in the app list and the first activity, you can choose between these options:
1.a) Set just the Application name in the Manifest.
<application
        android:label="@string/app_name"
        ... >
and don't specify android:label="@string/title_first_activity" 
for the first Activity. It will inherit the Application label.
OR
1.b) Set the Application name in the android:label field of the first Activity in the Manifest.
 <activity
            android:label="@string/app_name"
            ... >
            <intent-filter>
                  <action android:name="android.intent.action.MAIN" />
                  <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
 </activity>
The <application> item will share the same label of the <activity> item, whether you specify a value for the <application>'s android:label field or not.
The next step is:
2) Set the title for the first Activity at run-time in the FirstActivity.class
@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);
        setTitle(R.string.title_activity_login);
        //TODO: insert the rest of the code
}
In this way your first Activity will change his title few moments after it will be shown on the screen of your phone.