Why is Power Rangers Cosmic Fury lumped in with Power Rangers Dino Fury?

Well, an uncaught mistake might have been made due to a misunderstanding, especially if both cast and crew are identical, while the release info on every episode is similar or identical. Were there ever two separate IMDb title pages that were later merged? If so, then the IMDb data editors ought to look into the matter directly. If not, then a new page will have to be created, and then maybe some of the info migrated using the "Show title?" feature of the submission form, like explained at https://help.imdb.com/article/contribution/filmography-credits/how-can-i-move-credits-to-another-page/GYZQEK7ACM9KCUNA#, and the rest duplicated, or entire episode-type pages moved via the episode title correction method.