There are a few possible interpretations for why the poet says "Come" twice in the poem:
* Emphasis: The repetition of "Come" emphasizes the urgency and desperation of the poet's call to the horses. He's trying to connect with them, to convince them to come back to him, and the repetition shows the intensity of his desire.
* Two different calls: The two "Comes" could represent two different calls: one to the horses as a whole, and one to a specific horse (perhaps the lead mare).
* A broken connection: The two "Comes" could also symbolize the broken connection between the poet and the horses. The first "Come" might be a hopeful call, while the second one reflects the realization that the horses are gone, that the connection is lost.
* The poet's own internal struggle: The repeated "Come" could be a reflection of the poet's own internal struggle. He might be torn between staying with the horses and returning to the human world.
Ultimately, the meaning of the repeated "Come" is open to interpretation. It's a powerful moment in the poem, adding to the sense of yearning and longing that permeates the entire piece.
It's important to remember that poetry is subjective, and different readers may take away different interpretations from the same lines. What matters most is the impact the poem has on you personally and the thoughts and feelings it evokes.