Hedged Margin is funds which are necessary to open and support an open locked (hedged) position. In other words, it is the guarantee which is required to maintain an open locked position.

Here we point to an example:

If hedge margin is indicated 50% for a symbol, it means that the broker will take margin only from one hedged (locked) positions. Assume that you open 1 lot buy on EURUSD and the required margin for that position is 100 USD, after that you open 1 lot sell on the same pair but the margin will not change.

Hedge margin = 50% 

1 lot buy = 100 USD

1 lot sell = 100 USD

1 lot buy + 1 lot sell = 100 USD