It doesn't look like a duo profile, it looks like all you get is the one girl; Tia.
£60 you will full personal service and dressing up and toy show
£80 with specail services for half hour
£100 for the hour
£120 for the hour with toys and uniforms,
Those are singles prices.
I would say look on AW for any 18 year old girl in your region called crystal, it will likely be her.
If not then its just a friend and she is not an escort.
What you could do if you cannot find anyone is make an enquiry, how much to book both you and Cystal. Then Tia will reply with a price then you know she is an escort.
If she said nope she is not an escort then you know.
*Edit* actually it says
just finish hotel 2girls
£100 for an hour with 2 girls one 18 and the other 23 is a bargain amongst bargains. And especially uni students.
I would check to be honest as its very vague