Hobby Lobby Stores review: either a cashier mistake or a computer glitch... which?

Thursday, January 16, 2020: Don't we all know that all the items (without a credit sign and without any subtractions at the end) on the right column of the sales slip are our charges. I noticed a charge for $9.99 and under it a $4.99 which was the sale price of the same item (Paper Studio). So not only was I charged the correct half price of the item but also the full price on top of that. I also confirmed it later using the calculator. Also, Hobby Lobby does not use SKU numbers making it harder to identify a specific item. I knew I had no other purchaes for $9.99. However, when I told the manager this was a mistake, she doubted my honesty though we checked off all the items. I asked her if she thought I had it hidden in the car (since I'd already taken my purchases out and was looking over my slip). Her words: "Do I have to check?" "No!" I replied. I was embarrassed to think she suspected me of dishonesty, though it is conceivable individuals may do that. The cashier for the refund the manager authorized (not the orginal cashier) was very gracious saying that mistakes like that do happen.

My question is: How can an advertised sale item keyed into the system appear on the checkout charging BOTH the original price and the sale price? Will Hobby Lobby be able to address this glitch for those unsuspecting customers? The only solution I can think of is to never neglect checking diligently the sales slip before walking out of the store, though sometimes this can be difficult to do on a tight schedule. Your word may not suffice.