747-400 Go Around

[QAVION]

Not quite sure what happens during an Autoland if you push the TOGA switches twice....

If once, the aircraft goes into THR Mode and climbs at 2000fpm.
If twice, the aircraft goes into THR REF, but.... how is the extra thrust used?

Is it used for extra V/S or extra airspeed? If it is used for extra airspeed, what happens when you reach the flap speed limit? Does the thrust reduce... or does the aircraft start climbing faster?

This sort of stuff isn't mentioned in our engineer training notes.

Thanks.
Regards.
Q.