Auto Build Another Underground belt When Put It On Blueprint

[sh_zrui]

There are a pair of Underground belt and a pair of Fast underground belt.
When I put a Underground belt on the blueprint of Underground belt, The only one underground belt has been built.
But When I put a Underground belt on the blueprint of Fast underground belt, The two underground belts have been built.
The gif file can shows clearly.

I hope that when I put a Underground belt on one of the paired Underground belts, they are both built.