Are you using Lacerte?

This sounds like a ProSeries question. 

Here's the issue: "When I enter my clients recovery rebate"

You mean, their Advanced Payment? Or, Recovery Rebate Credit? Two different things.

Perhaps it would help to review what is really happening:

The funds were paid out as Advanced payment against a projection. The projection used 2018 or 2019 tax returns. But 2020 is the Actuals. You use the 2020 return to reconcile what a person is entitled to, against what they got.

"though they received the full amount"

They got money In Advance and no one had their 2020 data at that time; whether or not that is the Full Amount is just now being determined.

You will be entering their tax return data, which will let you reconcile what they are entitled to, as a Refundable Credit against the tax due, and you enter how much they got In Advance, which had nothing to do with what they were actually entitled to, because you are just now computing that fact.

"It would be easier to review to show amounts received and that none is due,"

But that might not be correct, and that's why this exists to be worked through.

https://www.irs.gov/newsroom/economic-impact-payment-information-center-topic-a-eip-eligibility

https://www.irs.gov/coronavirus/second-eip-faqs#Eligibility

One for each EIP.