"you do not believe the client should have the 1099 corrected?"

There is nothing wrong here. Why should anything be changed?

You don't have duplicates. You don't have overreporting. You have people that are subject to different requirements.

"Honeybook issued the client a 1099-K for all the billing in 2023"

If Honeybrook is a Payment Settlement Entity (PSE), they are required to do this based on thresholds of number of transactions and/or total $ handled. Read here:

https://www.irs.gov/forms-pubs/about-form-1099-k

"but the actual clients also issued the client a 1099-NEC for the services."

The clients are required to do this based on the total of services reaching $600 or more in total. What these clients don't know is that Honeybrook is a PSE. A client paying through credit card or PayPal, for instance, doesn't need to send a 1099-NEC. They don't know about Honeybrook. Sending a 1099-NEC anyway is not an error. It's an option. Read here:

https://www.irs.gov/pub/irs-pdf/i1099mec.pdf

"When I added up the 1099s (1099-K and 1099-NEC) they added up to double the client's gross receipts."

You don't add them together. That's adding apples and kittens. Neither of these is your client's business income. Each of these is a type of reporting. Think of them as two different Subsets of Gross Revenue. They might overlap, like a Venn diagram. They might not. Your taxpayer might have one and not the other.

If they have 100 clients in the year who pay $500 wach, there is no 1099-NEC required from any of those clients. Your taxpayer client still reports $50,000 of revenue on taxes. If that was paid by cash, there is no PSE. Your client still reports $50,000 of revenue on taxes. And if there is one sale only in the year, say $10,000, paid through Honeybrook or any other PSE, there is no 1099-K reporting requirement for Honeybrook or the PSE (at this time). Your client still reports that $10,000 of revenue on taxes.

What you are stating doesn't apply to what you are supposed to be doing.