Which name provided during booking a flight is the one that counts?

I wanted to check prices on a flight from Ryanair and because they wanted a name up front I entered "Test Me". After going through all the extra options that Ryanair provides and clicking through ~15 pages with offers for additional services and goods I finally came to the total price. Then I switched off my tablet and thought about it for a while.

When I opened up the tablet browser again 2 hours later, ready to book the flight the flight details were still there and I could just continue booking. By this time I completely forgot that I even entered something because in my mind I didn’t even start the process of booking yet. Also, during the whole booking process the name "Test Me" was never displayed anywhere, but my real name was.

So then I created an account using my real name and details, paid for the flight providing my real name and details again and finally I did an online Check-In, again, providing my real name and details and even my passport number.

When I then printed the Boarding ticket on it was the name "Test Me". When I contacted Ryanair about this they requested 160€ for a name change.

Long story short: Which name is the one that counts? And do I really need to pay to have the name changed, even though I registered, paid and checked in using my correct data as printed on my passport?