Contribution processor errors result in incorrect fatal error: "Contribution already processed"

3.2 doesn't appear to be handling payment processor errors properly. For example, if I use the wrong test CC for a PayPal test drive, I get "This contribution has already been submitted" fatal error page. Only after loading another CiviCRM page do I see the correct payment processor status error msg:

Payment Processor Error message
: 10759:Gateway Decline This transaction cannot be processed. Please enter a valid credit card number and type.

To replicates on sandbox ... do a test-drive on our sample contribution page 1 and use credit card = 4111111111111111

http://sandbox.civicrm.org/civicrm/contribute/transact?reset=1&action=preview&id=1

... and after submitting Confirm button, you get this fatal error:

"This contribution has already been submitted. Click here if you want to make another contribution."

I suspect this is related to some our session-handling changes.

... if you then load a different CiviCRM page, you see this status msg:

Payment Processor Error message
: 10759:Gateway Decline This transaction cannot be processed. Please enter a valid credit card number and type.