Hi,
my understanding of the computerised FOVE performance is that it looks for the maximum thrust reduction by using an improved climb technique (higher V2) to achieve 2nd segment and obtacle clearance gradient. The detailed results for a perf calculation give you a wide range of V1 options.
The only reason I can think of for a higher V1 with TOGA would be if you were VMCG limited and needed more rudder authority with full thrust on the live engine. Maybe the lower V1 with TOGA is the lowest safe useable V1 for TOGA ?.
I have also wondered why on some long dry runways, V1 comes out so low when there is plenty of room to stop well beyond V1
(edit. just seen previous post which is far better than my limited explanation)