Basically the way this game describes duplo libido is like that, wanting to fuck every biped that looks vaguely humanoid.
Except that the ones with the highest libidos we've seen have all been monos, Fiona is constantly horny and all the big pushy girls on the CQ path have been monos as well. Not to ignore Natasha who's constantly pushing for sex with everything that moves.
I generally agree with the idea that duplo libido is highly exaggerated for bigoted reasons, but that doesn't necessarily preclude duplos from having a higher libido than other people either.
I think that it is important to make the distinction between having the "highest libido" and having a healthy sex drive be a part of your life.
Fiona does a bit of the whole "locker room talk" stuff and is generally open with her sexuality and able to "return fire" when things start heating up, but I would hardly call her a sexfiend. Zoey on the other hand...(I know Fiona was the one that introduced the vibe panties into play as a gag but I still think Zoey is like 95% responsible for that sleepover ending up as horny as it did)
Also Fiona has other hobbies, her mmo gaming, rpg groups, seemingly stable job situation, etc.
Ashe spends most of her days early in the game and before its start just shut in her room masturbating almost all day. Fiona is her only friend that manages to get her out of the house for anything but her job, and her job is also in a relatively precarious situation. Her concerns about her libido are constantly haunting her thoughts and also guiding most of her decision-making (iirc Ashe justifies her smoking weed as being a way of numbing her libido).
There's a valid discussion to be had about how much Ashe's problems are caused by her traumas and the discrimination she suffers, rather than a direct biological consequence of her being a duplo. But I would not say that her problematic relationship with her sexuality and constant need to suppress it indicates that her libido is any lower than Fiona's, and neither would I say that Fiona's libido is necessarily high just because she's more open about it and comfortable with it.
I don't recall a number or indication of the % of duplos in EI, does anyone know? (Might've been mentioned somewhere)
I do not remember for a fact, but have the vague idea of "10%" in my head. No certainty and probably misremembering though.