The overprint on the 2nd didn't change the usage of it, it remained revenue?
No, Remains an Revenue stamp, I believe that is an automatic till impression, from a receipt.
You may be able to note a line of punctures
between the vertical script.
That new stamp image
Looks to me like the typical Currency Value Fount of TAIWAN
I'll have a dekko at my database
But feel I have never seen this before.