Within the sector's actual data field, there is neither any data correction nor error detection beyond this CRC performed by the drive controller. In case the second CRC fails, the data is still sent to the computer, but marked as defect. In case the first CRC fails, the drive cannot be sure what and where on the disk it has actually read - It wouldn't make much sense to send the data to the computer in this case - The host computer simply gets a "Sector not found" message. They support a simple CRC (error detection), both on the ID fields (the sector header identification) and the data sector itself, to be able to identify they have found the correct sector on the disk and the data sector is intact.
Standard Floppy controllers don't have any error correction at all. (Answer based on WD1770, a prominent standard Floppy Disk controller from ~1980)
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