rustbelt wrote:
Yeah, Howard the Duck is already collected as an Omnibus. But it's long OOP & now a very expensive volume.
When the Eternals Omnibus also went OOP & prices skyrockted on eBay, etc, Marvel did not wait long to release two TPBs.

True, Howard is due as a TPB, if I were to guess Eternals sold better then the duck, basically Marvel saw a market there and went for it.
Or it is possible retailers asked Marvel for more Eternals reprints, because it sold fast at the shop while Howard didn't.