Not with normal items.
Certain recipe items that have a slayer property did give a chance to get a second slayer as an additional property, but this has been sporadic, at best, since theymade some changes to the property generation system to keep weapons from having two different "hit (spell)" effects.
Since that change occurred, some people have claimed to have still gotten double slayers from the slayer recipes (Butcher's War Cleaver, Slayer Bow), while others have stated that they spent hundreds of runic charges with no doubles.