It is a double-hulled YAK-110"YAK-110" (which is two Yak-55's), it was only recently completed and will be at Oskosh 2018 (and so will I, so I may be able to add additional pictures in August).
Here is another video with the jet engine at its first airshow (and the picture you have is a screenshot from it):
It also isn't the only aircraft set up this way (jet/piston), the Screamin Sasquatch is another airshow aircraft converted to have both.