Search the lady's name for example, and you will see 3 ads the previous day by a different woman who only coincidently has the same name.

Three different post IDs because there are three different ads that are posted. Post ID refers to the ad, not the person posting. I think that sometimes the post ID remains the same, if the same ad is simply re-posted to a new date (it is then removed from its prior date).

It appears that some ladies simply post multiple ads in order to keep one of their ads near the top of the list. I would assume that this happens more often if they are experiencing a slower day. This has been going on for a long time.

Regarding the specific lady in the links you posted, I believe there was a thread about her on this board relatively recently.

Even if you convince me that good providers have unique, inclusive ids, why the concern about the id?

Doesn't sound too promising.

It does seem to be an anomaly if the "Other ads by this user:" links NEVER appear for her.

Doing a quick check does seem to show that there are also others that do not have the expected "Other ads by this user:" links.

Seems like it could be somewhat interesting to continue observe to see if there is a correlation between that happening and known B&S , for example.