Apologies if this is a known issue, but it appears that any district that had a special election or appointments to fill a vacant spot now has duplicate active legislator records.
For instance, Wisconsin’s 42nd House district shows Rep Ripp and Rep Plumer as active. However, only Plumer is the current representative. He was voted in during a 2018 special election.
This type of issue appears in what - very quickly - looks like around 50 cases from Arkansas 83rd to Illinois 47th (this was an appointment, not special election) to Hawaii senate seat 19th (also appointment), etc.
From a data perspective, it looks like these can be filtered by selecting the most recent date from the created_at field, and that will leave the user with only the truly active legislators when taking special elections and appointments into account, though I haven’t confirmed it works for every case.