Can two 1st order reactants in an overall 2nd order reaction have different rates?

I've recently done a saponification reaction of ethyl acetate with sodium hydroxide and used the initial rates method to find the order of reaction. (I change the concentration of one reactant and keep the concentration of the other one constant and find the initial rate for each concentration)
$$NaOH+CH\_3COOC\_2H\_5 \to C\_2H\_5OH+CH\_3COONa$$
My concentrations for each reactant is 0.5M-0.1M decreasing in 0.1M intervals and for the most part, the rates at different concentrations show that it is a second order reaction, and first order with respect to the reactants, which is correct. The only issue is, the initial rates that I got when I was changing the concentration of Ethyl acetate was much lower than the initial rates when I was changing concentration of NaOH even though both are first order. I've repeated this a few times and nothing changed.


Is there a reason for this happening or is this because of some methodological oversight?


Thanks in advance.


