Suppose I have two vials of Basic Poison:
You can use the poison in this vial to coat one slashing or piercing weapon or up to three pieces of ammunition. Applying the poison takes an action. A creature hit by the poisoned weapon or ammunition must make a DC 10 Constitution saving throw or take 1d4 poison damage. Once applied, the poison retains potency for 1 minute before drying.
I take an action to apply one dose to my sword, and then another action to apply a second dose. Then I hit a monster with my sword. Does the effect accumulate, with each poison causing an additional 1d4 damage (for a total of 2d4 on top of the normal weapon's damage)?
If there's no official answer, I'd appreciate any reasoning to help me make a ruling as a DM. I have a player whose character recently acquired an Alchemy Jug (which can make Basic Poison), and has asked me how multiple doses at once would work. I'm not sure whether poison ought to be something that is either there or not (and multiple doses wouldn't change anything other than maybe extending the duration) or whether applying more poison ought to be more harmful than applying less. Both interpretations seem reasonable to me.