Formula Question

I posted below but got no response - sorry to use another post.  Does anyone know if I can use two different kinds of formula?  Both are the same brand.

[kierstynsmommy]

I would ask your pediatrician what they think before I mixed formulas. I know that I mixed powdered formulas with my dd because she had reflux so bad, but it was a last resort kinda thing if you know what i mean, we had tried everything else before we mixed formulas.

[hopefully mother of 3]

I used to mix formulas with both my children. I wouldn't do it with every bottle of course, but sometimes I would have some left in a can cut not enough for a full bottle or I would get free cans of formula that wasn't our regular brand. I was told that it was kind of like mixing whole milk with 2%, it's different milk, but milk is milk.
Of course it is best to ask your pediatrician and not take my word for it, but my kids are healthy and happy.