Glow Lichen's Breaking Bug

If you place two Glow Lichen like in screenshot, two of them will be destroyed.

I think that it can be caused by merging two of this Glow Lichens - check screenshots. 

Is it intentional? I don't think so. 

May occur with vines, I haven't checked. 

How to reproduce the bug:

1. Place any block you like.
2. Place Glow Lichen on this block and on the ground.
3. Destroy any of this Glow Lichens.