For most cases, it should be the same, excluding some cases where there is a specific reaction occurring in the maturation of your accord, that will be prevented in the presence of other materials in your final formula.
So I believe it is safe to assume that if you add the same ingredients, with the same ratios between them, there is no difference if you will first mix them on their own, or otherwise on the order in which you add them into the formula.
One benefit of premixing an accord would be that you can mix some ingredients into it in a low concentration, which will make it impracticle to add them directly into the final formula while keeping the same ratios.
Should be the same, only thing I will say is depending on how large of the concentrate you are making it might be easier to dose the accord as such as opposed to individually adding.
If you are only going to make maybe 10grams, and the accord you use may only be like 5% of the formula and in that accord if there is something that is only .2% of the accord it’s a real microdose to get right.
For example in my rose base I use beta damascone at around .002 of the formula, if the rose base is only used at 5% of a 10g trial, I’ll never be able to dose the damascone properly, but I can easily dose the base.