In short, no, the individual photons are not actually being split into two new photons of lesser energy. It is true that in the classical interpretation of light, an ensemble of many distinct waves of photons, will create destructive and constructive interference patterns ( e.g. Young's Double Slit Experiment ). It is even more intriguing that these constructive and destructive interference effects are present even in the case of a single photon.
As an aside, when we mention photons, we mean the abstract idea that includes the wave/particle features inherent to an unobserved/detected electromagnetic wave. This is to say that until we make a measurement ( think delayed-choice ), these photons can and will behave as both.
To elaborate a bit on your question, we could ask, "Well, what about this individual photon is being split?"
Here is what I hope is an answer that intrigues you to keep asking more questions about this subject: In our attempt to control, predict, and describe our universe, we run into a problem when attempting to explain really small and/or fast things. This was first theorized with deBroglie's wavelength and Heisenberg's Uncertainty Principle accurately describes why we can not simultaneously know position and momentum with infinite precision.
So, what does this mean? It means that when physicists use quantum mechanics to predict things, they inevitably and unavoidably must use some notion of probabilities. Which by now, I'm sure you've started to guess at what will become split after a photon meets a beam-splitter. If not, that's ok, it's quantum mechanics...
In summary, a single photon incident ( fancy word for arriving at ) at a 50/50 beam-splitter ( common in quantum mechanics, and meaning that there is a 50% chance that the photon will transmit directly through, and a 50% chance that it was be reflected, and for the guys checking me: the reflected wave's phase will be shifted by 180 degree ) will emerge from the beam-splitter with a 1/2 probability of being reflected and 1/2 probability of being transmitted. So, it is the probability of the photon being in some output port that is split.