You stole the words right out of my mouth. I'll bet that both projects will start to borrow code from each other, assuming they haven't already.
Development of the encoder is possible because the HEVC is an open and public standard, originally publicly developed by the JCT-VC.
I thought that HEVC had several hundred patents as of a few months before it was even finalized. Did the owners of every single one of them give a patent promise? I don't suppose these patents were overturned by prior art.