Large Batch Data Entry allows multiple submits causing duplicate transactions

Transactions entered through batch data entry can be duplicated during submission (If I search for the contributions I will see duplicates for each contact that was entered in the batch. If I view the closed batch it will show the actual entries, but the assigned is double what was actually entered).

The problem is when submitting large batches it can take quite some time (15+ seconds). There is no clear indication on the screen that the batch has been submitted. If the person submitting then clicks the submit button again it creates duplicates of all the transactions in the batch! Considering there is no way to easily remove duplicate transactions this is a real pain to clean up.

Suggestions...
First, there should be something in the code to catch this, and prevent it from happening.

Second, I think the spinning CiviCRM logo should come up to indicate that it is processing the data.