Hello!
At WHO we are using an application called Bulk Load to upload data from excel. It generates templates automatically from any data set or even program on the fly. No complicated mapping needed. You can fill in the template an upload data. During the upload process it also detect duplicates.
The new version of this app was just released in case you wanna check it out!: Bulk Load app 3.5.1 now available
GitRepo:
GitHub - EyeSeeTea/Bulk-Load-blessed
Hope this helps!
Lucia