Why would they do that? Would it not make more sense to focus on existing customers instead of chasing new leads? I mean, sure, don't put all your eggs in one basket. But when an existing customer is asking you to take their money, why turn them down?
One company occupying the extra: company goes bust, you lose their business, probably spend months/years fighting with a bankruptcy holding company to get paid and maybe lose.
Two companies occupying the same space: same risk, but you still get paid for the extra space while dealing with it.