Hi OP,
It depends where you are going. Solicitors' firms usually look only at the overall grade. At the bar you would have a slightly tougher time. Of course, there is a very good way to explain away these things. E.g., "After my contract grade I realised I had to get better at commercial awareness and business dealings. I worked very hard, and took the optional commercial law module to challenge myself, and ended up with a 67".
Specialist firms may ask you in interview why you did poorly; that requires a smooth answer rather than better grades, if I'm honest.
Best,
LT