I am no expert, but I have played around with pictures. An amateur would find it easy to place those bears in that position. A total amateur like me could pull that off. Did you look at the rest of the pix at the Daily Mail? They looked like normal photos of polar bears in a natural environment. I think they were trying to create pity, not because the bears were being compromised by warming, but because they were cold and helpless and looking stranded.
No, I only saw the one. It doesn't surprise me that they might try to bury this fauxtograph among a group of real ones. There's an old axiom that goes "Hide in plain sight". It appears that's what they were trying to do.