in the past with US passports, when you applied for the new passport the old one was cancelled. I wasn't aware of the outreach service that allows you to keep your current travel privileges. But that's new from 3 years ago when I got my new book in the US. They were actually very clear at the passport office that even if I found my lost/stolen passport, as soon as I left the window the current book was not longer valid.
My other old passports were all returned with my new one, with two holes punched in it. I've also seen the cut corners from others on the group here.
What I've never heard of is someone applying for a new passport and having the old one remain valid unless it was granted a special permission (one for Israel, one for Arab countries).
They didn't take the time left on my TV into consideration, just said has to go to an embassy or consulate. I don't know that this is a rule, just my experience.
Getting the same message now in Chiang Mai going from my non-Ed -> non-b, have to leave. This is from my companys attorney, I've not been down personally to try. I've read online that some have successfully done it, but my luck hasn't been the same
I had to leave last year to go from SETV to non-ED, both Nakhon Phathom and Chaengwatthana said I'd have to go to Laos. Had plenty of time left on my TV. This was for Faculty of Graduate Studies at Mahidol, your uni may have a different way to do this.