Just noticed that actually
only compressed files are deleted during Text Mode-
txtsetup.sif
[SourceDisksFiles]
binifix4.cmd = 100,,,,,,_x,2,0,0 <------copied not deleted
undoren.cmd = 100,,,,,,_x,2,0,0 <------copied not deleted
ren_fold.cmd = 100,,,,,,_x,2,0,0 <------copied not deleted
_default.pif = 1,,,,,,,1,2,0 <------copied AND deleted
First 3 are not compressed, 4th is. Since write protecting USB does not generate errors while trying to delete nor cause delays, I'd not be surprised if expand functionality in setupdd.sys or wherever it is works the same way as if source is CD, but simply isn't generating errors.
I have also tried to rename both ~BT and ~LS folders to 1WIN_NT1.1BT and 1WIN_NT1.1LS hoping that $ triggers deletion, hex editing setupldr.bin and setupdd.sys (thanks
cdob) Text Mode install went fine, but files still got deleted