How this issue comes up in other grammar bits is more interesting to me, however. Particularly, how is {lo gunka be fa mi} currently parsed? If multiple FA are explicitly disallowed, then it makes sense to be able to claim that it means the same as {lo se gunka be mi}. (seems pretty useless) If multiple FA are allowed, then it would probably end up meaning something very similar to {lo gunka GOI mi} of some kind. And that opens a whole 'nother can of worms.
For me, I'm fine with never using either of these ideas, ever, ever, ever. It makes sense. I'd even be fine with having double-FA implying a si/sa/su-like erasure of the first instance. (That is, {mi lo gerku ku viska fe do} could be "I saw the dog -- no, wait, I mean I saw you.") That fits in more nicely with how GOhA pro-bridi are handled, where the repeated instances overwrite older occurances. It's extraordinarily functional for GOhA in conversation. If that were the handling for FA, I'd expect {lo gunka be fa mi} to be parsed as semantic nonsense, probably a mistake meant to be {lo gunka po'u/no'u mi}
Overall, I look at it as being a bit of a folly to assign a meaning to multiple FA, but if I were to go with anything, I'd take great care to be as consistent as possible with the other grammatical constructs. Just off of these, erasure seems most sensible to me.
mu'o mi'e djos