He is functionally saying that they have the same chances. This is why:
First round interviewees → first round offers, cutoff is set at X where X is the score of the lowest scoring applicant from first round offered a place
Second round interviewees + first round interviewees → second round offers. First, all second round interviewees which scored at least X are offered a place.
Then for the remainder of second round offers the cutoff is set at Y such that the remaining number of places is offered down the merit list to the lowest scoring candidate who scored Y, which is necessarily lower than X.
Basically, for a first round offer you needed to score X.
For a second round offer you needed to score Y.
However, if you interviewed in first round then you needed a higher score (X) to get a first round offer than if you interviewed in second round for a second round offer.
However, in the end, the cutoff for both first round and second round interviewees would be set at Y, and thus the chances are exactly equal.