Rarely in Shadow Era is there ever a clear right and wrong on what to sacrifice. The factors to consider can be put into a simple list, tempo, likelihood of drawing duplicates, relative worth to other cards of the same cost, relative worth of the rest of your hand, etc. etc.
However, there's another factor that I'll be covering today.
More than the odds of drawing more, I'm talking about how many of a given card you'll be able to play if you end up going through every card in your deck.
Say I'm playing as solo Darkclaw, for example, and my starting hand is Captured Prey, Captured Prey, What Big Teeth, Speedstrike, Evil Ascendant, and Bad Santa.
Now, WBT, Speedstrike, and to a lesser extent, EA, are all essential parts to Darkclaw winning. With four teeth and one Master Smith in the deck, every copy is necessary to outplay the x4 Stop, Thief or Focused Prayer I'm likely to pair up against. I play three Speedstrike, not four, so the likelihood of having another when I want isn't as high as I'd like. As for Evil Ascendant, I have three of them as well. Not as necessary a card, but still strong.
This leaves either Captured Prey or Bad Santa.
Sure, you have a duplicate Prey. Sure, there's two more in the deck, same as Speedstrike or Evil.
Doesn't matter. At the end of the game, you'll NEED four preys. In the same way that you need five teeth or one Ss. You need that pure quantity, that ability to match enemy threats one for one without expending too much SE on attacking allies. Sacrificing CP just isn't an option. It doesn't matter that you have an extra, nor that they won't be needed until at least T5. Every deck has a few cards like this, where their presence in your hand overrides any other preconceptions you may have about the sacrifice step. In these cases, quantity overrides quality.
Now let's go back and look at the rest of the hand... Bad Santa. As the only 2cc card in the hand, it feels odd to me saccing this on the first turn. Looking back over the hand, everything not Santa has the same cost, 3cc. This could be a whole other problem.
My eyes drift back to Evil Ascendant. The least necessary of all the cards in my hand, EA is overshadowed by the Teeth in my hand, which do effectively the same thing and then some. Keeping and possibly playing the Bad Santa on T2 will possibly wield another EA, but more importantly I'll need a sac for T2 anyways if I were to pitch the santa the turn before. Also, I'm still missing Lone Wolf. Playing that santa, even if it won't give me much for cards, still increases my odds of getting Lone Wolf on time.
In the end, the optimal choice is to sac the EA on the first turn, with the possible either playing or saccing of Santa on T2 depending on what I draw.