Congregation Support two separate raise spectre setups.

Shouldn't it be possible to use congregation in two separate Raise Spectre setups? One level 4 setup in gloves and a level 3 on chest via Uul-Netol's Vow.

When I try this approach, the max number of possible spectres on chest increases, but when I try to raise a new spectre with the chest setup, it will do one of two things:

1. Nothing at all.
2. Kill two spectres on glove setup.

Is this intended? Or is it a bug? Would a lvl 4 on both setups solve the issue?

Thanks