This is somewhat of a hack but it works:
First a quick example function:
Func3=@() deal(1,2,3);[a,b,c]=Func3();% yields a=1, b=2, c=3Now the key here is that if you use an variable twice in the left hand side of a multiple-expression assignment, an earlier assignment is clobbered by the later assignment:
[b,b,c]=Func3();% yields b=2, c=3[c,c,c]=Func3();% yields c=3(edit: just to check, I also verified that this technique works with [mu,mu,mu]=polyfit(x,y,n) if all you care about from polyfit is the 3rd argument)