"There sure is a lot of Undertale this round."
To satisfy my own curiosity, I gathered data on which games have multiple tracks in round 3.
Undertale does, in fact, have the greatest number of tracks still in the tourney, though not overwhelmingly so. With 4 tracks out of 64 active competitors, it is the highest number from an individual game.
Right behind at 3 tracks each are Deemo and Atelier Ayesha. The games with 2 tracks still in are rather well known titles: Bravely Default, Chrono Trigger, Dark Souls, Lufia (2): Curse of the Sinstrals, Xenoblade Chronicles Still a good variety of games represented this round.
Took some notes on game series with multiple entries still in. Nier, Ace Combat, and Persona have tracks from three different games present. Wild Arms and Final Fantasy have two representatives each. A different Atelier title has a track still in bringing the series total to match Undertale.
None of this is intended to be statistically significant. There's a number of games where only one track got nominated after all. A knockout tourney of 64 with 4 tracks each from 16 different games would make an interesting experiment; if I were less lazy about it, I'd consider running it.