Are we the dust from more than one dying star?

The statement by Krauss is highly inaccurate.

"Every atom in your body came from a star that exploded". No. Most of the hydrogen in your body came from the big bang. A large fraction of the carbon, some of the nitrogen and lots of the elements heavier than iron were made in intermediate mass stars that never exploded as supernovae.

"the atoms in your left hand probably came from a different star than your right hand." This implies that you are made up from the debris of only a few previous stars. This is a false picture. The Sun is the product of (at least) millions of previous stars. Stars more massive than the Sun have short lifetimes compared with the Galaxy. They live their lives and scatter their products into the interstellar medium, where it is mixed on timescales that are also much shorter than the Galactic lifetime. The Sun (and therefore you) will contain nuclei from a large fraction of the $\sim 10^9$ stars that lived and died in our Galaxy before the Sun was born.

The details are in the linked questions, but also see Origin of elements heavier than Iron (Fe) and https://astronomy.stackexchange.com/questions/16311/how-can-there-be-1-000-stellar-ancestors-before-our-sun/16313#16313

There is no definite answer to this question. Krauss knows the field far better than I do, but I would imagine he was simply stressing the general make up of proto stellar clumps, composed of elements from many stellar explosions.

Sure, we could have obtained all our elements from one star, in fact I asked a question Formation of Solar System, a while back on whether we knew what star it was that exploded and compressed the gas cloud that comprised the early Solar System.

But what probably caused Krauss's comment was the fact that proto-stellar clouds are absolutely enormous, needing the material from many stars, so the odds are that he is correct and it is likely that we are here now because of the debris of more than one particular star.

Please note there is a much fuller related answer to this question at Recyled Stellar Material .