What the hell?
Okay, there are 10 witnesses. If he doesn't distribute his stake into two accounts, each of the witnesses he votes will get a x sized vote.
Peter1 -> x
Peter2 -> x
Peter3 -> x
Peter4 -> x
Peter5 -> x
Peter6 -> x
Peter7 -> x
Peter8 -> x
Peter9 -> x
Peter10 -> x
If he splits his stake into two accounts, each of the witnesses will get a x/2 sized vote.
Peter1 -> x/2
Peter2 -> x/2
Peter3 -> x/2
Peter4 -> x/2
Peter5 -> x/2
Peter6 -> x /2
Peter7 -> x/2
Peter8 -> x/2
Peter9 -> x/2
Peter10 -> x/2
Peter11 -> x/2
Peter12 -> x/2
Peter13 -> x/2
Peter14 -> x/2
Peter15 -> x/2
Peter16 -> x /2
Peter17 -> x/2
Peter18 -> x/2
Peter19 -> x/2
Peter20 -> x/2
This gives each of his vote only half the influence.
Yes, the total quantity of stake voting is the same, the influence is smaller. Since he can't push so many people into the top ranks.
What I am talking about is that each piece of this pie is now smaller. This means that other people can more easily give bigger slices to other users to overrule his "now smaller slices".
So either, he has to give multiple slices to a user to match it (which then would negate the effect of splitting up the stake)