In all sites of app (in Spanish language) shows both links text: IMDb and TMDb, like IMDb. Reproducible: Always
Created attachment 96258 [details] screen-shot
Created attachment 96259 [details] screen-shot 2
The problem is in mo file. It was bad translated.
I've changed the po file in sources, I've compiled and I've opened the app but it still shows wrong name. Perhaps the problem is in source code of forms.
From your screenshot, it looks like you have two IMDB link fields in your collection. If you create a new movie collection, for example, do you have the same problem? If you do have two fields, could you delete one?
Both TMDb and IMDb use a lower-case 'b' officially. See http://www.imdb.com/help/?general/ and https://www.themoviedb.org/about.