Series I bonds limit for joint return

TurboTax limits purchase of Series I bonds to $5000 per joint tax return.

I have read several tax advice articles where the limit is $5000 per social security number.

Using the tax refund, How do I purchase a $5000 Series I bond for me and a $5000 for my spouse in TurboTax?

The software gags at anything more than $5000 for my joint return.