Hmm. Fairchild says about LM78XX: "Each type employs internal current limiting, thermal shut down and safe operating area protection, making it essentially indestructible." I think it is not so bad to use more than one in parallel. Sure, in worst case one will source all the current until it gets into limitation. Then voltage will drop until it reaches the treshold of the second regulator which will start to supply current and help the first one and they will keep voltage on the lower level.
Why do you think it will start oscillate more likely than a single regulator? Do you think the oscillation may be higher than the desired output voltage?