In what way is the FBI poly retest different from the first test? Are they the same "kind" of test covering all of the same topics? An acquaintance of mine (another applicant I met at an earlier stage) who had his retest recently, and he claimed there were no control questions. He thought it was a relevant/irrelevant test, but that seems unlikely to me. He also said it did not consist of the same areas - that it consisted of the drug section only.
it depends. it may be no different. once I told them I had polygrpah knowledge, they change the test around a little to try to make the contrl questions less obvious. They may try to "Yes" test you.