Here's the profile for the "Speed Racer" Actor "Rain" in IMDB, with the Profile name "Rain (III)" listed in the person's IMDB profile.
https://www.imdb.com/name/nm1713653/?ref_=ttfc_fcr_3_35 The reason for the "(III)" in the profile name is to dis-ambiguate the name to distinguish from the other Cast and Crew members in the IMDB database who go by "Rain". It is not part of the person's professional or birth name. It is simply a visual convenience for users to dis-ambiguate. Each person in IMDB does have a unique IMDB-ID for their name, but does not have a unique text name.
If IMDB has correctly normalized all the Cast&Crew names for people named just "Rain" in their database, there are approximately twenty of them that need to be dis-ambiguated, otherwise you will be crediting each of them with the work of all twenty of them.
https://www.imdb.com/find/?q=rain&s=nm&exact=true&ref_=fn_nme_exIt is a shortcoming in MyMovies that does not deal well with this kind of Name dis-ambiguation. Ideally, under the surface the database would hold the unique identifier (in this case "nm1713653") as well as the standard textname "Rain" and the dis-ambiguating textname "Rain (III)". The name management in MyMovies does not allow the end-user any real way to dis-ambiguate names in the application. It's a very real -- but very hard -- problem, and I don't know how you resolve it, other than maybe providing a "Sort Name"= "Rain (III)" that links to the unique IMDB-ID for the Name.
In any case, each Name record in the MyMovies database should include the unique IMDB-identifier (if it doesn't already), that is modifiable for users to be able to correct improperly pointed records. For example, correcting a reference to Actress "Rain" (listed by IMDB as "Rain(XV)" in their IMDB profile to disambiguate them) who corresponds to "nm11341443" that really should properly point to the Cinematographer "Rain" (listed by IMDB as "Rain(XXIV)" in their IMDB profile to disambiguate them) who corresponds to "nm14080394".
Similarly, the current Name management in MyMovies does not account for transliterated names well by not allowing "Alternate names" on a unique Name-ID that corresponds to the person themselves on lookups and displays. For example, I had to create a "Michael Cacoyannis" credit as this name was not found in the database. As his original name is Greek, in Greek characters, and has been transliterated in multiple ways, and he has used a "Westernized" professional name, the name of the director "Μιχάλης Κακογιάννης" is very complex to manage. It was in the MyMovies Cast&Crew list already as "Michalis Kakogiannis", which is not a form of his name that corresponds to any of his professional credits (usually listed as "Michael Cacoyannis"). Fixing this larger problem would be a huge project. You might look to how the American Film Institute implements their "authoritative name" database if you ever wanted to try to tackle this massive project (which would also involve normalizing all the names in the current MyMovies database.)
I hope this complex description was comprehensible.