I think I found it. Made a new preset, searched, found a plist and viewing it in BBedit, I see the new name.
com.apple.print.custompresets.forprinter.EpsonStylusPro3880_1E820D.plist (your name may vary).
It's in the Users Library>Preference.
That said, can't say replacing it on the new machine will work, worth a try.