That "spare" second rune

From: Richard Crawley <richard.crawley5_at_TuW84uUrys9Qy4GpnIt83JfvTvCMDM3vErm82PWe1rVVgMhL1zJBRQRxHAq>
Date: Tue, 1 Dec 2009 08:02:50 +0000

I notice that in HQ2 some of the gods have two runes but can only be "approached" through one of them. For example, I think Buserian has Truth and Fire/Sky but can only be initiated to through your Truth rune.

What in practical terms is the significance of the second rune? I know this isn't the forum for rules queries so how would Gloranthans perceive the difference between the two runes (if they are even aware of their existence in this context).

Richard C