If you have TO-1 or TO-2 selected for take off you must not select TOGA as you will exceed these thrust settings and so bust your VMCA calc. Also the same if you manually advance thrust levers beyond the assumed temp limit and as this is not indicated its easy to do.
Not according to the FCTM.
When using ATM, the takeoff thrust setting is not considered a takeoff operating limit since minimum control speeds (VMCG and VMCA) are based on the full rated takeoff thrust. At any time during takeoff, thrust levers may be advanced to the full rated takeoff thrust. (FCTM 3.15)
So a clear difference between using FIXED derate and ATM.