gogocarto sync
The biggest plattform with 20.000 Entries: https://www.colibris-lemouvement.org/passer-a-laction/agir-quotidien/carte-pres-chez-nous
gogocarto
collaborative editing of maps, fully configurable https://gogocarto.fr/projects
Source https://gitlab.adullact.net/pixelhumain/GoGoCarto
They recommend for syncing Semantic-Bus https://github.com/assemblee-virtuelle/Semantic-Bus - does that also check double entries?