Mixing two types of supplements

[pizdac]

Hey sorry that I Ask so many questions but its the first time I'm going to order from the US
Is there anything bad in mixing two different types of supplements like these:
http://bodybuilding.com/store/mt/nitro.html for extra mass
http://bodybuilding.com/store/nutrex/niox.html for extra muscles

And if you should have better products for extra mass I would appreciate

Thank u!

[Cammo]

Pro-lab's Nlarge or Cytosport's CytoGainer would be better IMO.
MuscleTech products are pretty expensive for what you get.