Yes, your daughter got $600 and you got $300. Rebate is more than $300 only if the tax on your income is more than $300. Read this:
The rebate payment will equal the amount of tax liability on the return (tax liability on the return Form 1040 line 46 or Form 1040A line 28) with a minimum amount of $300 and a maximum amount of $600 for individuals.
For information on stimulus tax rebate schedule, the eligibility and how much rebate you will get read:
Your U.S. Tax Return: Are You Eligible for 2008 Stimulus Tax Rebate Payment?