Since WSU doesn't hold a separate round of interviews for interstate applicants they don't have a formal 2nd round of offers
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MD Important Dates and Deadlines | Western Sydney University
In the 1st round presumably WSU will send to UAC a *ranked* list of its applicants for place offers. UAC will start from top down but skip those who also get a higher-pref UNSW offer, so WSU's last (110th) place may go to one who ranks say 150th.
When some of these WSU offers are later declined (maybe after getting a home state offer), without a 2nd round WSU could give them out as direct top-up offers rather than via UAC. The big question is will WSU give them to the 151st, 152nd etc or will they bother to check if any of the 1st-round skipped ones now want a second dip?