Do Special Attacks overlap or can you only ever have 1 in 1 attack

[CODESTA147]

For example, does Ring of Blade Echoes have lifesteal if you are using ancient sword, because the lifesteal is contingent on the special attack actually proccing.

[Kagora]

They will overlap and each take their chance at overriding your default attack,
You can hover over the attack icon for them under you attack interval bar and it will list the probability for each special attack you can currently use.

[Pandorian]

A special attack from Ancient Sword won't overlap and give you Life Leech when Blade Echoes is going and Blade echoes won't overlap and give you multi hit when Life Leech is going. The special effect is tied to the special attack. You can easily see this interaction if you were able to equip both at once. The life leech won't do multi hits.

In this circumstance you will however have 20% damage to all monsters if you're at 100% health(from the sword) when Blade Echoes is going.