I have encountered Insert and Delete errors after replication synchronization when the replicable objects include two tables in a one-to-many relationship. Delete errors seem to appear when only one record in the "many-side" table, relating to one record in the "one-side" table, is deleted from one member of the replica set. Insert errors seem to appear when one or more records in the many-side table, relating to one newly added record in the one-side table, are added.

These observations are entirely empirical and when these errors occur they are hard to sort out. Since I use replication on very simple databases (with only one user), I simply build a new database and create a new Replica set.