Hey mark,
The short answer is no. There is no management of tweens that target
the same property at the moment. I think you would get 'unpredictable
results' if you tried it. You'll just have to make sure to stop the
first tween before starting the second.
Feel free to add a feature request to the project site and I'll try to
add it to the next version (of course you're welcome to add that
feature yourself if you're up to it)
Mims H. Wright
http://mimswright.com