Neither. I'd look around to try and see if there was some kinda light reflection causing it to have two shadows,and if there was no apparent reason,run.
And also, no, don't bring Tennant back, Capaldi is needed to change the direction Tennant and Smith made it head into. I love them both, but a darker Doctor was needed. Enough of flirting with companions and wonderfully childish catchphrases for now.
Blink and you are dead.
ITS ALRIGHT MAN JUST READ THIS
I WAS NOT PREPARED
Or break down and wait for the Doctor.