The 1.03 trillion already includes the refundable tax credits, so using this approach those would be eliminated. Check the actual Senate report. There is no double spending in this case.
The people who currently pay income taxes would still be paying income taxes at the same rates. The only change would be how it's distributed.
Obviously there are multiple proposals for UBI with different structures. What I describe above is one of the simplest ways to do it given current taxing and spending levels.
Whether the societal changes were "people are enabled to accomplish far more in life" means economic value added or subtracted very much remains to be seen.