Two traders can enter opposite positions at exactly the same time and the same price (i.e. they buy/sell from/to each other) and they can both make a profit off the trade yet they are using completely different strategies that have them trade in different directions.
So how is this possible?
An example is the easiest way to demonstrate. In summary, the traders have a smaller target than stop loss.
Let's say that both traders are trading the ES and have a target of 1 point profit. Both traders use a 2 point stop loss.
The trade goes 1.5 points in one direction which causes one of the traders to exit at their target of 1 point and the other trader has had a draw down of 1.5 points. The market then reverses and moves at least 2.75 points in the other direction causing the second trader to exit at her profit of 1 point.