Photos look TGTBT, so after a little bit of research, I found another eros ad using the same photos as "Ivanka" from nyeuromodels:

compare:
http://www.eros-ny.com/files/277621.htm
http://2.bp.blogspot.com/-Q3mEAWrQ2wo/T7ysCyQNPEI/AAAAAAAABe4/pAWkMJV_bwo/s1600/ivanka+montage.jpg

Also, in Alina's montage, the lower left photo looks like a different girl than the rest, but the editor cleverly blocked the nose in every other shot to hide this.

The upper right photo in Angel's montage, and the lower right photo in Melissa's montage look remarkably like stock photos I've seen from another "high end" agency from years past, which was known for using fake photos.

I have forwarded your post to their manager, I will update with their response.

Crap!
I had Alina and Masha.
Photos are real.

I previously replied but it hasn't been posted by the moderator as of yet.
My post stated that I would forward your comment to the MY EURO MODELS and have them comment on this for you and the TER community.  The following is NY EURO MODELS reply:

Very often top high class escort providers are using different agencies to promote them. Sometimes agencies are using photos of providers to promote their business. For best results bigger agencies are using different photographers as every photographer have their own style. NYEUROMODELS are in a partnership with other worldwide and european agencies and they are using photos they took themselves and photos that was provided by their partners, employees, etc... ALL THE PHOTOS OF THE GIRLS ARE REAL AND AUTHENTIC! The best way to get more info is just to book a girl from either agency and see who will arrive after that you will be able to write a review regarding your real experience without guessing. Right now Ivanka from "euromodels" is not available till 23rd of july She left to visit her lovely sweet home in Russia. So you can guess what to do next

See my reply. The girls had a threesome and there is a TER review on it

Lucky me Ha-ha.

I have met Tiffany from nyeuromodels
Very pleasant experience.True photos of her. They even emailed me photos with face after we met.
Kissable. I would book her again if she would be here i believe She's coming back august.
Had previously also other girls from Ginas blog. all real.

What is the explanation of the other provider using Ivanka's photos (or vice-versa)?

NY Euro Models called them and discussed the situation and was basically told to fuck off
So I guess it's up to you to make an appointment and see if this lady arrives at your door.