The Jewish monarch is the person who leads the people of Israel, forges them into the unified nation that they ought to be, and keeps them living up to the highest of moral standards. Being that monarchy blinds people and tends to bring out less than ideal character, the Torah imposed strict boundaries and prohibitions on the king: not to have too much money, not to have too many horses, and not to have too many wives (Devarim 17:16-17). These are all understood as reigning in the excesses, which lead to haughty and arrogant behavior. But the monarch also is obligated with a positive commandment of writing a second sefer Torah for himself (ibid 17:18). Every Jew is obligated to write a Torah (ibid 31:19), but a king is obligated to write a second Torah for himself. As the passuk says: “It shall be, that when he occupies the throne of his kingdom, he must write for himself a duplicate of this Torah in a scroll form [the scroll] before the kohanim—the Levites.”
Most of the commentaries see this as a simple message to reinforce his devotion and fidelity to Torah; it is a symbolic gesture of saying, “I need to doubly reinforce my commitments, because of the responsibilities I bear and because of the temptations that come along with the position.”
But it seems that there is more to the understanding of the meaning of this obligation. After all, having a copy of the same Torah doesn't really seem to add to commitment and devotion. Rashi explains that there were two Torahs, one that lay in his home in his treasury, and one that would accompany him wherever he went. The two Torah scrolls were used in different locations.
This means that the two Torahs, although exactly identical in content, found very different application, relevant to their location.
If someone were to ask us, “what is the essence of avodas Hashem?” We would answer that the goal is to take transcendent spiritual ideals and values which are not really of this world and make them the essence of this world. Thus, giving away my hard-earned goods to someone who is in need is not a physical value, but rather a value that comes from a different world and a different reality. Having your physical drives and passions reigned in because of something called “sanctity”, is not a physical value. It is a value emanating from a world beyond.
In order to accomplish this, two steps are required. First, we must connect to a world that is beyond ours and become part of it. Then, we must take those values and translate them to actions and behaviors in our physical world.
We see this in krias Shema. The first paragraph deals with the totality of commitment to the beyond. It demands of us to give all our life, all our wealth, and all our desires and cravings for that which is beyond: Hashem. This represents a world that negates our world totally and is of a different order. When we have finished reading the first parsha we now need to apply it to this world. This is the second paragraph of krias Shema. It deals with integrating those values into activities that are of this world. Whereas the first paragraph deals with giving up our lives totally for Hashem, the second paragraph climaxes with our drawing life from that spiritual world into our very physical world.
The king, of all people, is faced with the duality of this task more than anyone else. When the passuk speaks of a Jewish leader, it speaks of the one “that will walk ahead of everyone and then bring everyone along with him” (Bamidbar 27:17). The king on the one hand must have those elevated and superior values that place him ahead of everyone else. He then needs to also know how to implement those values on the national and physical level so that all of Israel will perform based on those values. The king’s two sifrei Torah represent this duality. Rashi seems to bring this out by saying that “one sefer Torah remains in the treasure house. The other sefer Torah is constantly going with him on all his missions”.
There is an aspect of Torah that remains hidden and treasured in the vault. It is pure spirituality not impacted by the lowliness of mundane life; the demands of mundane life do not in any way affect the truth of absolute spirituality. But only leaving a sefer Torah there will not realize the purpose of it. He then must take a sefer Torah to wherever he goes and translate those values into common action. Even though both Torah scrolls have the same exact words, the king's focus is different, depending which sefer Torah he is connected to at that time. The first Torah is studied with the perspective of “what is the absolute spiritual pureness”, while the second Torah is studied with the perspective of “how to draw those truths into this very world”.
This same dichotomy is true of Klal Yisroel at large. There are the people of shevet Levi whose lives are focused on the purely spiritual. They are not supported simply out of expediency, i.e. because they don't have time to work. Rather the Rambam describes them as: “Why did the Levites not receive a portion in the inheritance of Eretz Yisrael and in the spoils of war like their brethren? Because they were set aside to serve G-d and minister unto Him and to instruct people at large in His just paths and righteous judgments, ...therefore they were set apart from the ways of the world. They do not wage war like the remainder of the Jewish people, nor do they receive an inheritance, nor do they acquire for themselves through their physical power.”
It's not a question of time or ability, it's a question of a mindset. Levi is meant to be someone that is beyond this world. But the other tribes are engaged in taking those very teachings and understandings that are inherently alien to this world, and integrating them into this world, so that the world becomes alive with divine inspiration. “Who is more important” is an irrelevant question, since Hashem’s objective here is that the values of worlds beyond this world are drawn into this world. We must have both halves.
The two sifrei Torah that the king has with him are the roots of both halves of Klal Yisroel. Thus, Klal Yisroel ascends the mountain to retrieve the purely spiritual, and descends into our physical reality and threads those values into the fabric of this world, taking the lifeless physical body of the universe and imbuing it with the soul and spirit of the beyond.