Do you perhaps mean a front handspring onto the board, and then a front handspring over the vault? Like this, but without the extra front tuck at the end:
In general, vaults with the front handspring onto the board are given a start value that is .1 higher than the "basic" version (just running and hurdling).
For example, in level 10, a tsuk pike is worth 9.7, and a zuhlke (front handspring onto board, 1/4 to 1/2 twist, back pike) is worth 9.8.
front handspring-front tuck is 9.7, front handspring on board-front handspring-front tuck is 9.8
front handspring-front pike is 9.8, front handspring on board-front handspring-front pike is 9.9
Since a regular handspring is a 9.0 in level 8, I would guess front-handspring on board-front handspring would be worth 9.1. Personally, I'd rank it a bit higher for level 8, maybe a 9.2 or 9.3.
Your best bet would be to have your coach contact your regional judging director to see if it would be allowed and to officially determine a start value.