But, from the looks of it, Krause does not use that KM number.
I do not have a Krause covering this century, but from Sjoelund's picture, it looks like this may be an error in Krause. Of course, if every other 2009-whenever coin has a different KM# due to the different portrait, it would make perfect sense for the 2 Euro piece to also have a different KM number. But it looks like Krause has not listed it like that, regardless of what those other sources say. And if KM#302 does not actually exist, I do not think we should claim it does. If it is KM#281 in Krause, then the reference number on Numista should still reflect that (and maybe even include a comment on the page indicating the error).
And of course, it is not like we will merge the pages just because Krause gives them the same number--Numista does not need to split pages based on Krause, and if there is an error, we definitely should not repeat it. And if this is an error in Krause, it may eventually be corrected. When Krause does that (possibly changing it KM#302, which seems chronologically likely), we can change the reference number to reflect that.
(And my request to change the reference number is still pending, by the by.)