Paralleling two VR - when neither is overloaded
No two regulators are alike and have small offsets from the nominal voltage, this can cause one regulator to take more of the load than the other. The easiest way is to put a small resistor to limit some of the current between the regulators if you don't have too much of a load.  See this article for more info. There are other ways to balance the input if they have a feedback pin, but in your application resistors should be fine.