The recommended ACA for light twins used to be 300' agl. The 300' used to be referred to as an 'engine out allowance'. The general idea was that if you commenced a single engine go-around in a light twin (any light twin) from 300' agl you'd be able to execute the manoeuvre without hitting the ground! So in principle it was good guidance, best practice if you will.
In reality most modern light twins don't need the full 300' and so the guidance (EOA)was gotten rid of. This then allowed CAA examiners to test down to lower limits hence the confusion surrounding ACA and where it came from.