Yes.
If you find you have methanol vials remaining from a previous order or project, they can be used for another sample submission.
They only caution to note is if the vials have been exposed to high levels of potential target contaminants. There is potential for the volatile compounds to contaminate the methanol if. If the vials have been stored appropriately, they can typically be used up to 3 to 6 months after receiving them.
Also make sure any sample and project information on the label is updated from the previous order.