On the the date night for both Mia and Chi you can get unique dialogue, but it depends on how many times you interacted with their AI versions. for how many times you have to talk to them before that night you can date them.
Chi (AI) - 2 times (on the 2nd interaction I chose the "take the credit" option)
Mia (AI) - 1 time
If you don't interact with their AI versions at least this many times, you get different dialogue when dating either Chi or Mia. For reasons why this many times for them, if you talk to Chi (AI) 4 times you cause her to erase herself on the 4th interaction. For Mia (AI) it repeats the same dialogue until after you date Mia, specifically if you talked to Mia (AI) once before dating Mia, you will be talking to both Mia and the AI at the same time and learn some interesting info. about them, if you didn't interact with Mia (AI) before date night, you just talk to only Mia.