I think they've been hiding. They for sure have never met. For the following reasons.
1.Sasuke would have soloed both of them simultaneously.
2. From what i understand from the spoilers. The cloak guy sent the blonde guy to see how powerful sasuke is. If they had met before and even had a little fight, it would mean they had to escape and would therefore know that sasuke can wreck them easily.
So what i think is that they have been on the run. I think the cloaked guy did something that called sasuke's attention. Then he figured out sasuke was on his tail, went off the grid and created that blonde alien lookong kid to take on sasuke. Probably brainwashed the blonde guy too.