Also a tee shirt company
crowcrow.com tee's are bum, but stop crowcrowing about it
From a crows supposed links with the devil.
As with many other English words used it became doubled to crowcrow to add extra meaning and to reiterate the sound.
crowcrow is also used to refer to an person who is mysterious / dark, such as a stranger who enters a villiage
He was not trusted as he was crowcrow, and before long he was force out of town