Hello!
The green-up action of the trigger (this is also the case with greening up manually) will "pick up" any bets you have on the selection and include them into the calculation of the green-up bet. So yes, it will green up on both the bets you will have by that moment.
If you want to place separate green-up bets for each bet you place, you'll have to make a trigger that "backs" (if the green-up bet is a back one) or "lays", and enter the formula for the amount of that bet, which is, in general case:
[price of lay bet * amount of that lay bet]/back_price - for backing
[price of back bet * amount of that back bet]/lay_price - for laying
The price and amount of the bet depends on your trigger settings and the attributes of the bet you are trying to green up, i.e. for £5 at 10.0 it will be 10 and 5 respectively.