Yes, this has been discussed in many threads.
If you stack, it's not recommended to take full servings of both because of the UroB.
If you haven't run them both solo yet, I'd do that, figure out what works better for me and full dose that in the day.
Not hating on OL, they deliver quality, but personally I didn't feel like I got a lot from these two. Massacr3 feels underdosed and Epicat I feel I don't respond to very well. I'd go for FD2, the Ecklonia Cava does wonders, plus I think the absorption package is better. Just my 2c