The critical bit is that the other e-fits they released were not of people in close proximity to apartment 5a at just about the time Madeleine was known to have been abducted.
In other words, it is hypothetically possible that a couple with no direct involvement in Madeleine's abduction might, technically, have somehow have secured custody of a child in good faith that just so happened to turn out to be Madeleine.
Separation in time and geography from the original incident (in Praia da Luz on May 3rd 2007) does not, automatically, carry the same pejorative connotation for the adult seen with a child hypothesised to be Madeleine.
The other point is that we simply don't know when the McCanns themselves came to be in possession of the e-fits.
We know, only, that Kate devoted considerable space to the Smith e-fit in her book (and, indeed, was/is of the view that Jane Tanner and the Smiths saw the same man.