Hello,
Actually the aren't rebranded, they are freshly branded new production KT77.
The one on the left, Russian made, the anode is classic EL 34 anode made with RFT anode tools. It looks to me like a real EL34, but maybe the grids are different and I can't judge that just from one photo.
The right one is Chinese made, with EL34 Shuguang welded plates and top mica with two side micas.
I'm not so big expert for current production tubes, but I suppose Russian one sounds better and it lasts longer.
Best regards!