The best way is to do this through a conditional filter.
1) Drag ABN to filter
2) Go to the Condition tab
3) Select By field, Number of records, Sum, >, 1
Filter in such a way that, ABNs have more than 1 record. If you have more granular data (e.g. different classifications of the amount), and Number of Records is not exactly what you're looking for, you can use BUSINESS NAME, Count(Distinct). That is proof for what you need (though a little slower)
If you want to learn more about tableau analytics then you can check our Tableau Course online.