The 'double-submit' test uses a counter that has its value incremented every time a DOM update is received. On submit the server receives the value of the counter which is compared against the value it holds on the server, when counter values have the same value the test assumes that there are additional submits sent before the browser received the update corresponding to the first submit.
The test fails when running with JSF 2 bridge queue because the submits that are put into the queue have their set of parameters already built. Submits taken out of the queue will be issued after the DOM updated is received but the parameters will contain the counter value the way it was before the update was applied.
In conclusion, the JSF 2 queue cannot really be used as a double-submit protection. Changing queue's behavior by calculating the parameters lazily, just before the submit is issued, will introduce other subtle problems (which we discovered in the past).
Porting the double-submit feature from 1.8 seems the only viable solution.
Initially assigning to Ted for the discussion part. Will likely re-assign back to Deryk for the development of a test application. The priority is set relatively high as we'd like to have the data as soon as possible so we can determine how much work we may need to do.