Compared to one-way trading, two-way trading allows traders to buy long first then sell short, or sell short first then buy long. That is, you are allowed to hold both long and short positions.
For example, Bob believes that BTC price would go up in the near future, so he buys long on hoo.com. But when he opened the contract, the BTC price went down. He thought to himself, “I’ll sell short at the moment. When BTC price goes up again, I’ll close my short position to right away to earn. Then if the price continues to go up, I’ll close my long position to earn more.”
Bob sells short so he now has a two-way position - both long and short.
So, two-way positions allow traders to make money no matter how the price changes.
Dec. 20, 2019