That's ... not how card fraud teams or credit card transactions or Shopify or any of this works, is it?
She's just popped up on my timeline on Twitter even though I thought I blocked her as even seeing 1 tweet a week was too much for me. She is like a dementor, sucking the joy out of life. So I speed read the thread and here I am.
No, it shouldn't be! Assuming the site is reputable, then the transaction will have gone through. Within 24 hours, it'll be credited if there is no order. What it sounds like she's done is press refresh on one of those screens that says "do not press back or refresh" so its taken the money conditionally more than once. Shopify and every half decent basket system does deal with this, but not always in real time.
This happened to me in early lockdown. I was buying something from Argos which is horrific site in terms of UI and speed. This will sound a little RM / JM. The cat decided to walk on my laptop and must have stood on F5. I have 2.laptops on desk - work & mine - so she likes to sit on the one I'm not using if both are on as they are warm. She's turned Edge into full screen mode with no menus, and best of all turned off the track pad when I have no external mouse. Anyway. The credit card company (John Lewis) said that were very confident it'd be ok the next day but to contact Argos. I did, they agreed it would resolve itself but if not call back in 3 days and they'd manually refund. Next day, credit appears on my account.
Despite the modern era of instant communication, loads of system still have "overnight jobs" that do hard work while there are no / less users on. Sometimes it is just because the systems on the background are shite. I could name 4 companies you'd all have heard of that are reliant on COBOL even though their web pages look all shiny and modern. I won't, cos I like my job, and perversely enjoy paying my own way in life!
As already diagnosed, sounds like a chance to rattle the tip jar to pay for the gin.
TL/DR she's not exactly lying but she's careless with the truth.