Alternate mode always provides equal or greater EPR/N1 to Normal mode at the same throttle position.
When the EEC automatically "reverts" to Alternate mode ("Soft" Alternate), it will latch in any difference between the Normal and Alternate mode EPR/N1 Command for that throttle position (sometimes referred to as 'bumpless reversion'). When the pilot selects "Hard" Alternate via the flight deck switch, any latched in difference will be immediately removed. That latched in difference can be anywhere from zero to over 10% N1 (depending on the exact conditions when the reversion occurred), so selecting Hard Alternate can result in a sudden, large increase in thrust.
BTW, rotor speed redlines are fixed, certified values - they don't change with flight conditions. Some engines do have a short time limit 'transient' redline that is a bit higher than the steady state redline value (and it's common for the takeoff EGT redline to a little higher - limited to 5 or 10 minutes). That's all part of the engine cert basis and documented in the engine model's Type Certificate Data Sheet (TCDS).