Not necessarly "fishy"!   Some do on other sites and some site are the same owners.  If it were wrong, then the ladies would be complaining as a post or two below.

Sometimes, multiple sites owned by same person

Sometimes, the lady shifts agency, new site quick to add, old site slow to drop

Sometimes, the agencies do not know she is working both boards

Sometimes, it is a highjack, lady's add is lifted, and included on service without permission - most common when there is large rate difference

Sometimes it is just a very old reference on an ad board not maintained

Really cannot tell other than to attempt to schedule and ask for confirmation regarding site/rate