kurnal makes a very good point. Provided that the two routes are fire separated (and if they're not you could probably compensate with AFD) you're only area of concern is the means of escape from all locations within the room to the doors from the room.
The objective, where there is a single door, is to get the last person out of the room in good time before the fire starts to be able to threaten those people making their escape. To achieve this objective:
You have to have very early means for discovering the fire and for raising the alarm in the room - I would think that with 80 people in the room it would be unlikely if not impossible that a fire not be discovered immediately after ignition.
You will need to ensure that the evacuation signal is spread very quickly - if there are functions taking place you will need facilities for killing music instantly, broadcasting the need to evacuate and perhaps raising light levels.
You shouldn't have combustible items near the exit doors - for example, keep coats in a designated area away from the doors.
You should have suitable policies, procedures for people with impaired mobility.
You do not have to discount one of the exits as they are being treated as a single exit and to discount one would be to discount both (which would be ridiculous - and precisely what the precautions I'm listing aim to avoid). Therefore, you can add to your argument that the two doors will give twice the flow rate out of the room and so the room will empty twice as quickly compared to a room with only a single door. Indeed, you might expect 80 people to evacuate through two doors in less time than 60 people would take through a single door. It would be hard to imagine it taking longer.
