Augmentation Evoker Momentum Shift question

I understand that Momentum Shift stacks up to 2, but I thought this meant we could potentially maintain that buff. Instead, my tests show that the buff indeed stacks, but it does not extend the time. So, getting a new stack with let’s say less than a second left on the original is a waste (although one could claim that a one-second 10% Int boost is better than nothing). My question is whether it would make sense to have the buff extended as well and give us a chance to maintain the buff.

and my tests show that it both stacks and refreshes the duration.

it just refreshes the current buff and stacks the %. It doesn’t go like 6s + 6s it’s just 6.