Empty "RMAPY" Batches

Hello:

What would cause empty batches beginning with the Source Document "RMAPY"? 

I know that, in a Multicurrency environment where payments are applied to invoices that are not in the functional currency, applying payments results in gain or loss financial entries that have to be posted. 

But, why would these batches be empty?  And, is there a way to prevent such empty batches from resulting?

Thanks!

John