For 6 October, I only see one incomplete registration with costs.

After checking in at Utrecht (16:00) a train ride was made to Woerden
If that was with the 16:25 sprinter, arrival at Woerden is 16:35
This fully explains the check-out at 16:37 (at normal cost)

What happened between that time and the 16:41 checkout needs to be investigated, it looks like some double check-out (with origin of travel unknown), or a 4-minute passage through the station.

No big deal, but of course the € 20,00 should be waived. The upper two transactions for 6 October at Woerden clearly indicate a ‘station passage’, and should be free. Same as the 3-minute passage on 30 October, which is correctly registered.

And then NS somehow made four registrations out of that second check out?

Seems like you checked out at Woerden at 16:37 and then decided to leave the station on the other side at 16:41 without checking in again?

This is an error because the gates on the other side should let you out without charge (already checked out) but I’m not 100% sure about that.

The 20 euros were not withdrawn from your bank account but from the balance on your card. See https://www.uitcheckgemist.nl/?locale=en but they will probably point you to NS Customer Service anyway.

It's unclear what exactly happened. I would advise you to contact customer service directly to speak to an NS employee about this. They can correct this and give you a refund. This can be done by phone; they are available 24/7 at 030-751 51 55. You may also contact them by chat (click the link Chat with NS on this page) or by sending a message on X (formerly Twitter) or Facebook.