http://www.fudzilla.com/home/item/26127-origin-auto-adding-steam-purchased-ea-titles
i can personally confirm this - started up origin today to find medal of honor was on it - and i bought that in the steam sale.
Electronic Arts is auto-adding EA titles that were purchased from Steam to a user’s EA Origin account. According to what we have been able to uncover, a number of Origin account holders have seen Dead Space 2 and Mass Effect showing up in Origin as games that they own
i can personally confirm this - started up origin today to find medal of honor was on it - and i bought that in the steam sale.