Hi Cameron.
I have used dual Accounting Schema, using same Accounting Elements and Two currencies.
One Accounting Schema has Country Currency as Example (Euro €)
The other Accounting Schema has Foreign Currency as Example (US$ )
You have to deal with Conversion Rates on Currency Window definitions.
When you enter AR or AP invoices they are entered in the currency they were made ( Some on € others in US$)
Idempiere takes care of doing Accounting Facts on Both currencies depending on Conversion Rates Rules.
It is importan also to check that Accounting TABS on BPartners, Products, Warehoses, BP Group, etc.
They Must have two registers, one for each Accounting Schema.
I hope this help to you
Regards
Luis Amesty