The entirety of the Lord Share goes to the Duchy as the Lord is also the Duke (Thus leaving no Lord Income). The entirety of the Duke Share goes to the Realm as the Duke is also the Ruler (It should show no gold under the Total Duke Share, only the full amount under Realm Share).
That 732 gold includes all the income you got as Duke/Lord/Knight. That is why it's nice for the Ruler to have Dukes also as Margraves / Lords of Rich Mountain regions. Their full income as a Lord/Knight is also taxed by the Realm Share.
