I don't get this gripe that the OP/child must have an affiliation to the number eight to be able to use Octavia. Millions of people call their son Thomas - we don't bang on about him needing to be a twin, do we?!
Anyway, they are due in September - being twins, high possibility of being early and thus born in the eighth month, August.
Ooh, OP, what about Octavia and Augusta!
As for words that are used as names, there are PLENTY of names that double up as words, but they are still used:
Mark (dirty stain/mark my words), John (toilet), Lou (loo - toilet), Will (left behind by dead relative/will he won't he), Bill (dollar bill), Cliff (rock exposure), Kurt (curt - precise), Peter (to peter out), Dick (ahem), Matt (small carpet), Jack (lever up a car), Abi (abbey - monastery), Gail (gale - wind), Sue (take to court), Dawn (morning), Di (die - expire), Neil (kneel - get down on knees), Rob (steal), Toby (mug), Jim (gym - exercise place), Barney (argue), Carol (Christmas song), Grace (prayer said before a meal), Scott (get off scott-free), Dom (dominatrix). Etc etc!
I prefer the names OP has come up with to many of the other ones I see here.