They are very similar. They are both PPAR regulators. I would just use one of the other. I personally would pick gw. It has been around a lot loner and has a lot more user feedback behind it. SR9009 has only been around a little over a year and the user feedback has been a bit controversial. Some seem to love it, some seem to say it does nothing.
Cardarine (GW-501516) - the best GW-50 - Evolutionary.org
Cardarine is drug that binds to the PPAR receptor and is non-hormonal. Cardarine increases the expression of genes involved in the expenditure of energy, stimulates glucose uptake in skeletal muscle tissue and burns fat by stimulating fatty acid oxidation.
Take 20mg of cardarine gw per day. 10mg AM 10mg PM