Funny thing is that the HiFiMAN CEO himself said Deva has "magnets on BOTH sides" (though asymmetrical) in a video interview on YouTube with Resolve from the Headphone Show YouTube channel.
Go look at this starting at 17:01 and at about 17:15 where he says "magnets on both sides" and
@Resolve asks, "magnets on both sides for the Deva?" and Fang responds, "yeah"..
. At mark 17:29 he explains that it is an asymmetric design with smaller magnets on the inside, bigger on the outside, and then he repeats at 17:42 that "for this very project... we use magnets on both sides."
So someone here is confused or not being honest -- there were early prototypes seen of the Deva with a grill that looked like the Sundara in design but silver-colored, and perhaps Fang was confused and talking about an earlier prototype of the Deva (which later was adopted by this HE-5XX) that had magnets on both sides and then later they changed it to single-sided, perhaps, but in this interview, Fang unambiguously says the Deva HAS "magnets on both sides."
The talk about Deva specifically starts at about mark 13:58.