Stackable poison

Seems if you eat poisoned food you can get poisoned, twice. Since you cannot cast it on someone who has it already, I figured this was a bug. Here is the log: <100%hp 100%m 100%mv 1241tnl> eat steak You eat a steak of the corpse of An eating dwarf servant. You choke and gag. <100%hp 100%m 100%mv 1241tnl> g steak sack You get a steak of the corpse of An eating dwarf servant from a large sack. <100%hp 100%m 100%mv 1241tnl> eat steak You eat a steak of the corpse of An eating dwarf servant. You are full. You choke and gag. You can no longer find the strength to wield a practice sword. <100%hp 100%m 100%mv 1241tnl> aff You are affected by: Physical malady: 'poison'. Physical malady: 'poison'.