Multiple companions + Loyalty support gem = does the damage redirection stack properly?

As title, i'm using 2 different companions, which costed me some hard to get gear with + Spirit and minion levels etc, and each has Loyalty support gem for 10% damage redirection (the companion takes 10% of the damage for me, i'm assuming it only works if they can take damage and they are alive obviously lol). So, if i have 2 of those active, does it mean i have 20% of the damage redirected to them? Please GGG it needs to be truth as it's very hard to get AND may not even be up 100% of the time