To give more insight into it, other than just my word, this specific question isn't really answered specifically by any of the rules documents. But there have been discussions on the forums about it as well as some I've had with Arcane Wonders employees directly. To explain the rationale behind it though, I want you to forget about the original question for a little bit.
MrBubu is partially right in that there's only one time period designated as "after a creature action phase". However, nothing limits you to only one effect during that time period. You could reveal multiple enchantments if you wish to, just for an example. There's no place in the rules that says you're limited to just one effect between phases. In fact, multiple sections (such as the enchantment section) say very plainly that you can do multiple effects.
However, any effects you use at this time, are basically occurring simultaneously. The time after a creature action phase isn't broken up into multiple steps or phases. It's just one time period. If you want to do multiple things at that time, then they're all happening simultaneously and you're merely choosing the order to resolve them in. That's why if both players want to do something during that time, you have a timing issue that has to be resolved by Initiative. Everything up to this point is clearly supported by a reading of the rules book.
So, now, if I have two things in play that both have an IMMEDIATELY after a creature action phase effect, then I can trigger them both simultaneously and choose the order to resolve them in. The immediately doesn't really matter due to the circumstances of the situation. Everything is happening at the same time anyways. This is the part that isn't really clarified by the rules, and makes you wonder why they put "immediately" on the cards to begin with, but it is the logical conclusion of the rules.
So, that's the thinking that got us here. I know, that line of thinking breaks down a bit when dealing with two effects that have to occur in a specific order, such as casting something before you can use it. They clearly aren't happening simultaneously. But, think of it as they're happening so quickly that they might as well be simultaneous. The time between phases is the blink of an eye, more or less instantaneous.
