I combed through Stephen E. Whitfield's The Making of Star Trek to see what I could find.
There is no reference to titles of the other two stories that were pitched along with "The Cage." However, after their viewing of The Cage, as we know, they ordered another pilot. On page 134 of The Making of Star Trek the other stories are stated to be Omega Glory by Gene Roddenberry, Mudd's Women, but Stephen Kandel, and Where No Man Has Gone Before by Samuel A. Peeples. It also states that "Roddenberry was taking no chances on a more 'cerebral' script this time -- all three represented strong action-adventure scripts."
I could not find any reference to whether any of these three stories were the same as, or in any way related to, the original stories pitched with The Cage, but it states that it was after _The Cage_ was rejected that they brought in Peeples and Kandel. Still, that doesn't make it clear if the two were writing original stories or writing stories based on notes or an idea or other previously written stories.
I would consider The Making of Star Trek as the most authoritative source on the very early days of the series, since it was written even before the third season aired, with direct access to Roddenberry, Gene Coon, and others. Whitfield was able to gather information before people were too involved and memories became fuzzy.
However, I found this web page Star Trek Tribute on Angelfier. Considering this is essentially a personal page on Angelfire, I'm not sure how authoritative it is, but it states that Gene Roddenberry's Original outline for "Star Trek" was Dated March 11, 1964. And ran 16 Pages in length! In addition to it's descriptions of the series' concept and characters. It contained several story spring boards, including two which ultimately became the finish first-season Episodes "Charlie X" And "Mudd's Women"! (as Spock would Say "Fasinating".)
It does not state that those two were THE two other stories submitted with The Cage, but it's worth noting that one of those stories was fleshed out as a possible 2nd pilot.
Note: The Making of Star Trek is a LONG book and I haven't read it in years, but I'll be checking through it to see if I can find more information on this in other chapters on other topics.