Welcome to numista :)
For the purposes of numista, I think this falls into a similar category as Zimbabwe / Rhodesia. Same country, two names.
Zaire was Mobutu's renaming of the country after his seizure of power - in a nutshell, these things are always more complex than a single statement. However, for the our purposes, I would consider the current placing of Zaire as correct, especially as the country name change was reversed after Mobutu was ousted.
The dropdown menu of ruling authorities under Congo already lists the Mobutu period as a separate ruling authority.
The 'Zaire Republic' is also already listed as a separate heading.
Some basic data needs to be entered for the Congo sections. Looks like there is no referee for Congo at present, so making changes may be slow.
Still, numista flourishes when members with knowledge of countries share their knowledge, and make necessary edits, I think you could make changes and add better pics.