cTrader and MT5 use different approaches for hedged positions. On the cTrader platform, when a position is perfectly hedged (meaning the symbol is both bought and sold), the margin is calculated based on the trade direction that has the highest volume and margin requirement. For example, if the total margin required for Sell positions is greater than that for Buy positions for a specific symbol, cTrader will calculate the margin only for the total Sell volume.
In MT5, the margin requirement for perfectly hedged positions is zero, however, the margin percentage must be a non-negative figure.
A perfectly hedged positions may be closed out if the overall account margin percentage falls below 0%.