i'm willing to bet they know about this and don't care
my guess? steam has an automated discount applying algorithm, and the likeliness of the algorithm enabling one of these auto-sales for a product is agreed upon with the devs.
however, if steam also has manually set discounts, like this one for example, it's completely possible activision gave steam the green light to set the discount on the digital hardened edition and the other deal just happened by coincidence, which benefits activision because they went out of their way to set the digital deluxe discount, so having nobody get to use the regularly scheduled discount means it'll go longer before the game is discounted again
alternatively, both games could've been discounted by the same auto-algorithm, and it just happened to disc' em both. this is actually a good thing for activision because having different versions of the same game go on sale at the same time in this likelihood-based algorithm means that, from the consumer's perspective, there's only one real choice (the better discount). because of this, salvo-firing discounts is actually a lot better than firing them off independently, because it'd mean at least one version of the game is discounted more often

see this handicapped graph? think of it like this: blue and yellow/red are the two versions of the game we'll call X. we'll call the versions y and z - blue being y, and yellow/red being z.
now, as i mentioned before, people will always just buy the better discount. so if Xy and Xz are on sale at the same time, there's only one economically meaningful sale - whichever's the better deal.
this is where we model Xz as the red dashes. on this graph, there are 6 meaningful sales in the given time period if we account for dual-sales only becoming one meaningful sale. however, if Xy and Xz get sales on different dates (this is where we model Xz as the yellow dashes), then the graph displays 11 sales.
in short, in a really, really convoluted way, this weird ass double-sale is either a harmless mistake or a deliberate move