Whichever bottle was not left open to evaporate is probably more accurate.
jkjk
With two samples, there is no way to determine which is right- especially not for anyone online, on a forum. That is why they sell a standard solution, which you can compare your results to. To make sure that your reagent is good. Ive been in the same place as you, typically I left a bottle open overnight or something. New reagents test the same, so I conclude that if a bottle reads differently, I messed up.
If you need an alk reading ASAP, I would take a reading again from each solution, and then if they still give differing readings, take the average. "good enough", minimizing the effect of an inaccurate bottle of reagent. critters should be find with a .3dkh difference.