[Warcry - Legions of Nagash discussion]

The ability says specifically its the same model being brought back. And the rules say a model cant activate twice in a turn. That makes it pretty clear to me.

Whenever possible you want to bring back dead guys that havent activated yet this turn.

[Warcry - Legions of Nagash discussion]

Im not a big fan of skeletons at all.  Offensively they just arnt good. I prefer running necromancer, 6 seneschals, and 1 graveguard.

Seneschals and graveguards do absolutely crazy amounts of damage for their points. And you get to bring 1 back to life every turn.

2 skeletons just dont compete with 1 Seneschal for damage. Yes you can argue the merits of using skeletons as roadblocks. But you can also argue the merits of outright killing enemy models so you dont need to roadblock in the first place. Seneschals do that.