If you decide clearly in your mind it may benefit you yielding definite reasult, perform a critical analysis for remaining portion of each group and see if you can complete & revise any group. As if you are preparing fo Final examination there is a very high possibility that your preparation is not of required level. I wil suggest go 4 quality in one of the groups rather then inviting all mismanagement and frustration for both groups. Good luck. Please dont worry its just an exam I know how difficult it is as I have passed it bt key to performance in last days is not to get stressed.