There was no information it's forbidden, same as no information killing only 1 WB is forbidden, to be honest. So how can we know if something is allowed or not?
When you enter the toilet, there is no sticker that says "you must not poop into the wash basin" and yet you know you must not poop and no one has to tell you.
A situation in which, after fully beating WB, we get 2 items and a 24-hour cd on further fights, it means that you should get a maximum of 2 items for 24 hours.
If it turns out that after killing one of two bosses, you get one item and you don't get, for example, 12 hours of cd, only 0 hours, 0 minutes, 0 seconds, then something is wrong. Especially if he does it 10 times and you get 10 items in an hour or two, something is wrong. I wouldn't like to use bad words, but I don't understand how you can think it should work that way.
Please, let's respect each other and don't treat ourselves like idiots, if we've done something wrong, let's be adult people, let's take it on the chest and don't try to whiten ourselves.