You can do a two-way sync. But it works like this: first a one-way sync in one direction (source>target) and next a one-way sync in the other direction. If you insert data in both between sync jobs you will have do define the Primary Key in such a way that the same PK-value is not created on both.
There are dozens of similar replies explaining (and also more elaborate) the importance of understanding how Data Sync works with the Primary Keys of tables..