Fields populated twice in mongodb


I am using Mongodb and have definded a schema. However when I post data through the API, some fields are populated twice. Once with the correct naming from the schema and another time all in lowercase.
Eg. “createdByUserId” gets saved correctly and then it saves it again as “createdbyuserId” with the same exact data.

I’ve even dropped my table and started from scratch to see if it helped.

Has anyone experienced this?