What does the title "Same Song" signify in Pat Mora's poem, considering the son and daughter's concern about their appearance?

Your interpretation of this poem's title is a sound one, and is supported by the poem's final word, "too." The poem is divided into two sections: one focusing on the speaker's daughter and her concerns about her appearance, and the second focusing on the speaker's son and his similar concerns. Although the two sections are divided, that final word, "too," unites them—it is the note on which the speaker leaves us, and it resonates in conjunction with the title. The girl's experience is, in many ways, different from the boy's: they are concerned about superficially different things, but there is a sameness in their self-criticism that is far greater than these differences. The girl's daily makeup ritual may look different to the boy's weight-lifting and jogging, but both are fundamentally the same thing, "the same song" of a teenage desire to improve what they see in the mirror, something that makes both of them "frown."

Unfortunately, because there is no group for Pat Mora or for this poem, I have to leave it in the overall Literature group. You sould as if you have cracked the meaning of the poem, however. Clearly, the way that the poem is structured in two stanzas, both of which deals with the two children of the speaker and the different ways that they feel forced into practising behaviours that they don't necessarily want to practise to satisfy the demands of society of their appearance and the way they look. Note how both daughter and soon peer "into that mirror, mirror" and frown at their appearance. Also I am sure you identified the allusion to the Sleeping Beauty fairy tale, where the evil stepmother looks into the "mirror, mirror on the wall," demanding to know if she is the most beautiful "of them all." Mora seems to be bemoaning a society that causes children to take such an obsessive interest in their looks and prevents them from being happy with themselves. Both girl and boy sing the "same song."