No, you don't get a second choice.
Certain employees who were put in FERS by mistake could choose to stay in FERS when the agency discovered the error. If they declined FERS, the agency placed them in the correct retirement plan (CSRS, CSRS Offset, or Social Security only). If you already had this opportunity to choose between FERS and CSRS, CSRS Offset, or Social Security only; then FERCCA does not give you an opportunity to change your decision.
FERCCA may help you, however. If you worked for the Government before you came under a retirement plan, you may be able to get retirement credit for that service by taking an actuarial reduction in your retirement benefit instead of having to pay a deposit. The same may be true for any military service you have. See the questions under the heading
Service Credit for more information.
Also, if you were in FERS for at least 3 years of service before your agency gave you an opportunity to stay in FERS or have your records corrected, OPM may compensate you for any out-of-pocket expenses you incurred because of the error. See the questions under the heading Out of Pocket Expenses for more information.