When ADB is started, but the port is already occupied by a different tooling, it logs an E/ddms message, however it continues with the execution.
This is indeed faulty behaviour. The port should be configurable, if the port is occupied - it should fail with Unable to start container or unable to connect to the running container exception - similar to behavior you experience with other remote / managed containers.
INFO: Connecting to the Android Debug Bridge at /home/kpiwko/apps/android-sdk-linux_x86/platform-tools/adb forceNewBridge = true
10:01:23 E/ddms: Could not open Selected VM debug port (8700). Make sure you do not have another instance of DDMS or of the eclipse plugin running. If it's being used by
something else, choose a new port number in the preferences.
Sep 27, 2013 10:01:23 PM org.arquillian.droidium.container.impl.AndroidBridgeConnector initAndroidDebugBridge
INFO: Android Debug Bridge was initialized in 350ms.