Again: I don't know if this is a bug or if there is a logical explanation for this:
When I destroy an Eclipse/Nightfall from my opponent (with Deflegration or Explosion) the effect from Eclipse/Nightfall is reverted (the +1/+2 is taken away from the creatures). If I steal Eclipse/Nightfall the effect is not reverted. So when using Steal the opponent still have the +1/+2 effect, but he does not have the Eclipse/Nightfall anymore.