The "Custom" settings you show are the default settings for "Custom", but can be changed according to need.
Those default "Custom" settings might appear to be the same as for "Two way", but are not exactly the same.
The difference is mostly in case files get deleted from one of the two locations.
In case of "Two way", such files will also get deleted from the other location.
With the shown "Custom" settings, such files will be "restored" from the other location
to the location where they had been deleted.