Logically it would surely be one or the other for us? Assume VVD is first choice, if he gets injured before we complete the signing then we're knackered. Koulibaly as plan B.
But if they're both available, and we've got the money - why not?, it does nail down succession for when Fonte's time is up. That's a lot of bodies in the short term though......Fonte, Yoshi, Gardos (when/if he's fit), Caulker, VVD & this guy.
I guess the key question.....is Koulibaly better than Fonte?