[Death Knight][PvP[PvE] Abilities that use 2 Runes vs Death Runes

[Dreadblade]

Wowhead/WoW Freakz Link: N/A
Descrierea bugului / Bug description: When you have 4 Death Runes, with none of them being on cooldown, whenever you use an ability that costs 2 Runes it should use 2 different types of death runes (e.g. frost+unholy). Instead it uses 2 Death Runes of the same type (e.g. 2 Unholy)

Dovada / Proof: First, because I use an addon for runes, here's what they look like normally

http://i.imgur.com/TLrEAgS.png

In the following screenshot, I used Death Strike while having 4 death runes up, and it consumed 2 death runes of unholy type.

http://i.imgur.com/GdOGNGT.png

It happens with any ability that consumes 2 runes. In this screenshot, my Festering Strike consumed 2 death runes of blood type.

http://i.imgur.com/a03hoFh.png

Proof that it should use 2 different types of death runes:
https://youtube.com/watch?v=Qmr1fhVYU0Y:

at 4:52