Thanks George, my original answer was wrong. Here's a less wrong, and this time negative
(1) says that: for all agents a, a knows that P
(2) says that: for some agent a, a knows that P
The meaning of (1) follows from the fact that epistemically necessary propositions are such that they are true in all epistemically accessible worlds of all agents (this second "all" is the key, because each agent has her own epistemic accessibility relation). The meaning of (2) is straightforward: "P is known" simply means that there exists someone who knows P to be true.
In case it's not already obvious why (1) and (2) are not equivalent, let's fully unpack the meanings of the two sentences. Each agent α has an associated accessibility relation R(α). Using this, we observe that:
(1) says that: for all agents α, for all R(α)–accessible worlds w, P is true at w
(2) says that: for some agent α, for all R(α)–accessible worlds w, P is true at w
Based on these observations, we can present a counterexample to the equivalence of (1) & (2) by having a world where some agent α knows P, but some other agent β does not know P. This situation would show that P is known (by someone), but nevertheless not epistemically necessary (because at least one agent, viz. β, doesn't know P).