I think it is very important to consider the sources of the spiritual information that you gather in your research. I do not think it is a good idea to regard any text as being completely doctrinal and without fault, and by the same token, I do not think it is a good idea to regard each potential source as being of equal value.
Such titles as “evening star” or “queen of heaven” don’t seem to carry much meaning. Perhaps they may briefly describe a quality or “calling card” of a certain spirit, but assigning deep significance to them seems far less useful than relying on the results that a spirit brings you, and on the impact they have in your world that you may not necessarily have been expecting, but discovered through directly working with them.
On to the actual topic, as has been mentioned we should clarify which system of magick we are talking about here. If you are referring to the Goetia, then there are a number of problems to address. For one, Amaymon is not one of the 72 demons, nor is Astarte, nor is Asmodeus (unless you assume that Asmodeus is a variation on the name of Asmodai, which does seem reasonable enough).
While we could attempt to cram every spirit that has been known as a demon into a single system, that seems ineffective, especially when you consider the Goetia as a piece of a larger Kabbalistic framework, where each demon is paired with a Shem angel and angelic emissaries.
With that being said, then perhaps we should consider these demons in the framework provided by the Book of Abramelin. Here, it is said that Astaroth, Amaymon, and Asmodeus (which was changed to Asmodi in a later work that expanded on the Abramelin to better reflect the original pronunciation) are all Dukes serving underneath the four Kings of Lucifer, Leviathan, Satan (renamed Shahtan), and Belial.
The text states that Astaroth and Amaymon are distinct spirits, each with their own unique demon servants beneath them. While the Abramelin itself does not provide much detail in the way of how to summon the demons or what their powers and qualities may be, a recently published grimoire known as Lucifer and the Hidden Demons provides an accessible, workable method into the magick, with the powers of the Kings, Dukes, and most powerful Servants elaborated upon thoroughly. Working with this system makes it very clear that these are not the same demons.
I must admit that I am not at all convinced by most of these arguments stating that one spirit is the same as another, particularly when these spirits originate from completely different traditions. If you want to argue that spirits have similar functions or are similar in terms of their powers and qualities, then I could see a reasonable and interesting point to be made, a sort of meta-metaphysics.
Where I think the trouble comes in is when one starts to equate all these different spirits with each other and tries to jam them all into one system, as what comes out appears to me to be little different from the chaos magick practice of invoking Superman or Dumbledore. Different powers and qualities are assigned to a symbolic entity, and then that entity is put into an often free-form and somewhat loose magickal operation without much of a connection to any historical methods or frameworks.
Now, I am certainly not saying that we should not try new things and attempt to bring innovations to magickal practice. Chaos magick at its height seems to have been a rather good influence on Western magick in general, as many of the old superfluous practices, such as wands and other such implements, have been replaced by more potent processes of the imagination, and without the “free-form” attitude of the Chaos paradigm people may have been more reluctant to try to simplify and expand our practices.
I am also not saying that all newer practices are without value. If the magick works, then it works, and I’m certainly not one to argue with results. What I would suggest, however, is that some techniques and sources are more reliable and effective than others when it comes to receiving high-quality results, both in the practical and the mystical sense, and that some sources are more susceptible to mutation and corruption by those with pre-existing assumptions and beliefs, particularly when those assumptions and beliefs are shaped by the prevailing religious attitudes of the time.
To conclude this lengthy post, I will reiterate again the importance of carefully evaluating the source of your information. Perhaps a tired reminder in the era of Fake News, but one that I think holds especially true in the now digitized and increasingly mainstreamed (to a small extent) world of the occult that we find ourselves in today. If you made it this far, thanks for reading I suppose.