The jaunty and primitive "Parade of the Ewoks" contrasts strongly with the more sophisticated music of the other characters (though it is somewhat comparable to the jawa music from A New Hope), and bears similarities to Sergei Prokofiev's "March" from The Love of Three Oranges.
The two are clearly not identical, or even near-identical (as was the case between the Star Wars Main Theme and King's Row), but there is indeed a strong resemblance.
First of all, the melodies use similar pitches. For the sake of comparison, in the examples below the "Parade of the Ewoks" has been transposed to match the "March". The red lines, then, indicate identical pitches. Both the Williams and the Prokofiev use A flat frequently, and play with the note C - sometimes it's C natural, other times it's C flat.
There are rhythmic similarities, as well. The rectangles in the example below show identical rhythms between the two. In addition, both excerpts conclude with a long(er) held and relatively low note, illustrated with the dotted line.
Although the above illustrations only includes the first two phrases of both pieces, the similarities do continue further in. The primary melody of the "Parade of the Ewoks" is answered by a trumpet fanfare that also resembles the Prokofiev, as illustrated below.
In this case, there are no definite pitches to cite, but the intervals are comparable, the rhythms are again similar, and the melodic contour very similar.
The strongest relationship, however, is not in pitches nor rhythm but rather in character - both are rather ridiculous marches (the score for "Parade of the Ewoks" is marked "A la marcia") that share tempi and border on absurdity. Orchestrationally, too, the comedy of both is heightened by the prominent use of the piccolo.
While not as evident as some other Star Wars borrowings, there are undeniable similarities between "Parade of the Ewoks" and the march from The Love of Three Oranges. With that in mind, it's a pretty safe bet that George Lucas included the latter on his temp track for Return of the Jedi.
The Music of Star Wars
These posts will help focus and develop my analyses of John Williams' film scores.