Not a lady who has changed her name and now goes by something else but current ads in the same city on different platforms using different names.  Same lady - same photos - same phone number.  Different names.

I would probably have to see the ads as well.  
Is she using 4 or 5 different names on 4 or 5 platforms? Or is it just two names? It could be a scam but there could be  innocuous reasons as well.  
Using multiple names across many sites is suspicious and you are right to be skeptical but again, I would need to see more to have a better idea what she is doing.
I seriously doubt its to track where leads are coming as most are smart enough to know that can be disconcerting to her current/future clientele. They can track their leads without the need for multiple names.

I've seen cases where an agency lady will operate under one name for one agency, and then operate under another name with another agency.

I saw a provider a couple of years ago under one name, then she popped back up under another name but had ads on Eros under her old name but P411 under her new name.  She was GFE, and within my price range so I saw her again and had another great session.  When I asked her about it, she said that she was breaking away from the agency and trying to establish herself as an independent.  

Sometimes you get providers trying to straddle both ends of the marketplace. One provider will have a high end persona with more GFE and a more affordable one offering HH and QV. Think of Toyota/Lexus or Acura/Honda, they sell the same car but one has more options and leather seats so it costs more. Maybe a mid to high end provider needs some extra cash here and there so they'll take lower end bookings. Maybe they are trying to transition to high end but don't have the reputation/booking volume yet to stick to that market. The idea is, if you found their ad on one site you would say "hello is this ________" and based on the name they can tell which ad site you found them on and how much they will charge you.  

There is no such thing as a "high end" client. Have none of you ever seen 'The Wolf of Wall Street' or heard of this gent by the name of Robert Kraft? I have had gentlemen from every socioeconomic strata book with me. So yes, the multiple persona at different price points can for sure backfire badly when your "high end" client is looking to sow his oats and finds you running an ad for half what he paid for the first round. I really don't think there is such a thing as low or high end sites to advertise on anymore, it has really become reputable sites vs non reputable sites which has to do with the screening process required to be listed on the site and does not at all reflect how much it costs to place an ad (I am talking about you, Eros!!). I advertise on multiple sites but I do cross reference all of them for easier verification on the client end and my price point is identical on all sites as well.

I was seeing a super-hot girl in LA for about $400/$500 for Greek. After a short respite I tried to book her again and she was gone! A few months later she reappeared under a different name at $600/700. I saw her again and I asked her why the name change. She said it was easier to establish a new identity at the higher price point, rather than moving her prices up by 50% or more! That made sense to me.

I understand why providers hate EROS and its high fees, but I still think it is the best site from a client perspective. Partly because the high fees act as a filtering mechanism and introduces a bit of survivor bias. The providers on Eros can afford the high fees, they must make good money to afford the high fees and to make good money they must be good at their job.

There does seem like quite a bit of bait and switch there, but I never concern myself what mainstream site a girl advertises on as I only care if I can verify her. Most guys, imo, dont have a clue that Eros has much higher fees as that doesn't concern them as that is more of a provider issue.
I agree about Tryst as it is an excellent site. It is easy to use, professional looking with large photos and many filter options to narrow down the db search. I think that is far more client friendly and informative than Eros. To me, it's not even close.  
The "old ads" you mention on the two sites arent really an issue at all because they fall to the bottom of the listings over time. IOW, they weed themselves out without any extra hoops to jump through for the client.
The benefit of the last site you mention is that the ladies control their profile and their "no list" which makes it easier for finding compatibility with a client. No other mainstream site has that feature that I am aware.

I have had more than one client say they were scammed from Eros, that is why I do not advertise on their site. Because of their high cost many mid and low range gals did not use them and because of this the scammers moved in. So it is not the cost of placing an ad that has me concerned, it is the fact that they do not do as much as tryst to confirm the person placing the ad is in fact a real provider. I would say your filtering mechanism may have worked well maybe 5 to 8 years ago with the assumption that the higher cost to place an ad would deter the scammers, but from what I have heard from clients it has at times been the opposite, i.e. it deterred the real providers and the scammers moved in easily as it was well known as "reputable" ad site and does not do as thorough of a verification process as they should.  
Any providers that use the free option on tryst or have not logged on for 3 months their profile will disappear. From their website the highest option is $163 a month and will have the "boosted" search so they will show up on the first few pages of the search. They also have the ability to post up to 40 pics. I would assume once you have filled in your search engine options this will greatly reduce your options and then I would say it should be safe to stick to the first 2 or 3 pages for provider options.  
I honestly started my private delights account but never finished the verification process so I am not on the site and do not know how reputable they are.  
If sex work can be decriminalized we would not have to play these games and jump through hoops, yet here we are....
Good luck!!!  

I agree about Eros, you beat me to it. I don’t like the assumption that if they can afford expensive ads then they’re good providers because maybe they’re just good scammers.  

One more name, one more profile, more people talking.  

I just checked on the tryst website and it says 90 days of inactivity the profile would be pulled. They *may* pull some early for other reasons. When I am not touring I let mine go back to the "free" option to keep my profile up but I do log on every few days  just to keep it active. Maybe if someone makes a profile but never logs back on maybe they get pulled? Honestly not sure.

Perhaps they don’t like the reviews.?