We'll be fooled if you stupidly repeat my mistake: we'll save that as an "abiility augment" even though it was already an innate ability of the familiar.
When I get home from work this evening, I'll add code such that if you successfully feed a pokepill to a familiar to give it an attribute it already has, it'll store "None" as the attribute in the setting, which will mark that familiar as having eaten it's single allowed pill, but will not screw up familiar ability detection.
The setting - and the code I added to let FamTeamRequest feed pills to familiars - would allow a "famteam [familiar],[attribute]" (say) command to feed pills to familiars only if the familiar has not been feed one yet - and to avoid triggering the KoL bug by refusing to give Spiky to a familiar which already Spiky.
(I'm not sure what cli commands/ash functions people are interested in to support this path. My other thread, inquiring about what would make things easier for consult script authors has gotten zero response so far from people who are interested in writing (or have already written) consult scripts for Pokefam battles.)