You are right to wonder if your first sentence is correct because it is not. I don’t have the exact grammar explanation, but you cannot name someone after using “de…”. However you could just say

J’espère ne pas m’être trompé de docteur.

In this case, if you want to call the person by his name I suppose it will have been dealt with beforehand, like in the introduction? (“Cher Docteur XXX,…)

Edit: I am assuming here that XXX is the person’s name. After a second thought I find the question a bit strange because I think in English you wouldn’t say something like « I hope I didn’t reach the wrong Dr. Smith »?

There is no reason to consider you first sentence as incorrect.

You can indeed write that when you believe there is a possibility for several doctors to share the same name and prepare the recipient for a possible mistake.

I haven’t found occurrences of trompé de docteur XXX but here are some similar constructions:

• Toutes mes excuses pour ma réponse, mais si je me suis trompé de Robert, ma sympathie à ton attention est identique.

• — Ah bon ? Je me suis trompé de Julie. Ce n’est pas le numéro de ma fille ?

• Avant son spectacle, Jamel Debbouze s’est trompé… de Vernouillet

• Désolé. Je me suis trompé de M. Pickford.