FMC calculates balanced field speeds. No idea why V1's should be different. Do you use de-rates or only assumed temp's from max thurst; and from what max N1%, 22k, 24k or 26k? If you look at V1 for different derates, this could be an answer.
For difference in N1% the reason is the left N1% is showing Bleeds Off values and thus is higher than the Bleeds On value of right engine. However, the difference on our a/c is only 8%, so your numbers are curious.