[Edit to rephrase some things and to remove the spoiler markings now that it's aired in the Pacific Zone.]
So, the first broadcast of duels is over.
Individual pairs were determined by the producers, apparently intended to pit similar performers against one another.  Then for each pair an off-screen coin toss decides who performs first.  The viewer doesn't choose between them but rather gives each of them a separate yes or a no (an abstention after checking in for a vote is probably a no, just as in the auditions).  The celebrity experts have 7% of the total apiece as in the auditions.
The one who goes first performs with the wall up and gets the advantage of gauging audience reaction (an audience that includes the opponent, as each gets to watch the other).  Then the wall goes down, the second performer comes on (with the advantage of knowing how the opponent performed and what score is needed).  The threshold for raising the wall is breaking the first performer's (E/C/M) score, instead of a flat 70%.
The winner from each pair plus the highest West Coast scorer among the other three move on.
The app showed the score for the first of each pair (Alice J. Lee, Megan Tibbits, Will Roth) in blue and the second performer's (Lisa Punch, Sarah Darling, and Jesse Kinch respectively) score in red if it didn't beat that of the first performer, blue if it did.
Results are up at http://abc.com/risingstar
but I'll summarize them here for readers:
Lee over Punch, just barely; Tibbits over Darling, just barely; Kinch over Roth by a wide margin.  In the E/C/M zones Darling's losing percentage equaled Lee's winning score.  As the only winner who performed second of the pair, Kinch was also the only one who raised the wall.
In the Pacific Zone, results were similar.  Punch and Darling both scored 67% there, but Punch's 67.43% was higher than Darling's 67.34%, so Punch got the wildcard spot, while Darling and Roth are out of the competition now.
Of course, since this show was only one hour long, ABC could have aired it at 10 PM EDT and the whole lower forty-eight could have watched simultaneously with no East/West split.  Too late now.
Next week's duels are April Lockhart vs. Sonnet Simmons, Austin French vs. Adam Jaymes, and Macy Kate vs. Gabby Nicole (Macy Marshburn vs. Gabrielle Tyson if you prefer).  That will leave four pairs for the third week of duels, so it is a disadvantage to be dueling in the third week if the PDT viewers can save only one of the four who lose in the E/C/MDT vote.  Then again, if the producers want an even number of winners for a second round of duels, they can't pass five people on July 27, but rather four (which would disenfranchise the PDT viewers) or six (which would make being on in the third week of duels an advantage).  We'll see how they handle it.  It seems that the number of installments the show needs to run depended on how many contestants passed the auditions the first three weeks.  All we know at this point is that Groban referred to the next round as "the semifinals."