You are correct. QT machines will spit out the same ticket stock with a barcode on it.
Not to nit pick, but it may be worth pointing out that we might want to change our habit of saying barcode when talking about e-tickets. The e-tickets do not use barcodes, they use QR codes which are the funny looking squares. I do not know how important it is to differentiate, but there could be confusion.
Looking at mine, the QR code simply contains the reservation number and the date the reservation was made.
QR Code stands for Quick Response Code. It's the next version after BAR Code. QR Coding is faster to read than BAR Coding for IR machines. The bottom line speed of checking passengers in without compromising accuracy. As long as an Amtrak rep (Gate agent or Conductor) have a BAR/QR Code reading IR Machine, all they need to see is the BAR/QR code and your Photo ID.