Games with the same name has been a somewhat long running issue.
Theres no rule of thumb over which game “wins” per sae. Sometimes it’s the older one and sometimes it’s the newer one. It’s a magical mystery black box.
Twitch itself just doesn’t handle duplicate game names well.
Theres a few uservoices on the matter, but it’s not something this forum can help resolve.
I believe the leading uservoice on the matter is this one Twitch category name collision – Twitch UserVoice
Here for all we know the newer games dev made a request thru uservoice and it was moved over to priotise the newer game.