On AdEspresso, we report conversions for both your Main Goal and all the other events you are tracking with Facebook pixel. When creating a campaign, at Step 2 (in the "track goal conversions with Facebook Pixel" section) you decide which is your Main Goal for your campaign.
For the purpose of this example, we can choose Purchase as the main goal - and attach to the purchase event a value of $100. However, you can also track other events that are sending revenue-information when they occur, like Newsletter Subscription (for example, you know that subscribers have an added lifetime value of 15$, and you are also tracking those subscription to your newsletter).
Now, in the campaign's Dashboard, you'll see two different metrics:
Main revenue only reports conversions for your main goal. That is, if you set Purchase as the main goal, this figure will show only conversions for Purchase. In the example, it will show $100 every time a purchase occurs (Purchase event).
Total revenue reports conversions for all the events that occurred due to the advertising campaign. So, if you decided to track revenues for Purchase + Newsletter Subscription, it will show all conversions occurred for the two events you are tracking. In the example, for a user that made a subscription and purchased, it will show $100 (Purchase event) + $15 (User Subscription event) = $115.
Note: if the Add to cart event has a value, as well as the Purchase event, but users don't purchase (so you'll see 0 conversions for the Purchase event) after they add a product to the cart on your website, you'll see the Main Revenue as 0, while Total Revenue will be higher!