A lot of people are overlooking this post. I tested this for myself on a target dummy. Glyph of disease did not reset the tick timers and therefore wandering plague can proc twice:

Keep in mind, the log excerpt was taken after using Glyph of Disease to refresh the dot duration.

Highlord's Nemesis Trainer suffers 703 Frost damage from [player's] Frost Fever.(175 Resisted)
[Player's] Wandering Plague hits Highlord's Nemesis Trainer for 732 Shadow.(182 Resisted)
Highlord's Nemesis Trainer suffers 809 Shadow damage from [player's] Blood Plague.
[Player's] Wandering Plague hits Highlord's Nemesis Trainer for 894 Shadow.
This is actually true rofl.
Diseases, even tho they are refreshed with Glyph of Diseases, are procing separately since the first application was PS > IT.

@DarkenedHue
What did you do?

@topic
Regardless, 20% extra DMG on Frost Fever is better, duo to the fact that IT + PS + BS will do more dmg than SS + Pesti most of the time, and give you extra GCD on top of extra Runic Power aswell.
http://forum.warmane.com/showthread.php?t=326654
This is a copy pasted guide of a retail best in slot guide for UDKs. Even here you can see that for single target GoD is not better than GoIT.
You can bring this up all you want, in the end nothing will change and GoIT + GoDD + GoTG will be the best combo for Unholy, when it comes to single target fights, regardless of what gear or last couple of talent point variation you use.
GoD will give you nothing but less DPS in the end.