Short names on Boarding cards?

Hi there guys, long time flyer, first time poster.

This year I've arranged to get my brother and his girlfriend over to Norway for New Years.
However, when adding baggage to their flights I noted that I'd recorded her name as Becky on the boarding card.
On her passport its Rebecca.

Will this cause an issue, how exact must the passport to boarding card be?
I've not checked in yet, but 220 pounds (there and back) seems a bit much for getting it dead on.

Any advice?

Thanks in advance.

Rick

Sorted.

Only cost me 20 pounds. While I feel it was more to do with the fact that an extra ticket would have been cheaper (always worth looking into), the fault ultimately was my own. Yet, theyve really surprised me here.

Thank you Ryan Air!

Always good to hear positives