From the pictures here and your prior descriptions not at all surprised by that combination. That's got to make them a lot of fun while they're still in puppy mode. Having the two together will obviously keep them playful longer than they'd be as singletons. But at what general age does this breed normally "grow up" and lose its puppy-ness?
At about 18mos they are cosidered "grown", or a better word might be "mature". They won't get much bigger in size than they are now, but all of their coat will not come in until about 18mos. At now 7 months, they are WFO when they are awake...you'd think they were killing each other they play so hard. Been a couple of "puppy fights"...but when push comes to shove, Rider's size and muscle mass will get the best of Tango, but otherwise, he lets her pester the chit out of him. He's about 2 lbs heavier, and that ratio will remain about the same. He'll end up at about 18-19, and her, about 15-16. They feel much heavier when they hit your chest or shoulder sitting on the couch
Rider is plastered up against my leg, with Tango laying curled up next to him as I type this. It's early afternoon nap time...