Basically if you stack a merger/splitter, more than once without moving upwards or downwards and just stay at the bottom for example. Then it will construct itself inside an already constructed merger/splitter instead of continuing upwards in the desired direction.
I feel like when you stack it once, you shouldn't be able to stack it further unless you move up to the stacked merger/splitter.
How to reproduce:
1. Place merger or splitter
2. Place two or more on top without moving upwards (as in don't move the mouse)
You should see it construct inside itself even though it should be encroaching its own clearance.