Like how crimson days engrams were locked to make sure players get only new items? Because it would be a pretty big slap to those still supporting bungie if we were back to the forced random nature when people are already grinding crucible for armor that all players will be able to level to.
-
It works like the crimson days event. You wont get duplicates until you've obtained everything else. If you preview a solstice engram you'll see a check mark on the items you've already obtained.