I noticed that calling .AddressCheck() on the following returns a 1 or true with a DPV value of AACC but the same parsed fields:

1. 7800 Dayton Rd Apt C 13 Fairborn, OH
2. 7800 Dayton Rd Apt C 22 Fairborn, OH
3. 7800 Dayton Rd Apt C Fairborn, OH

Result:

.Address = 7800 Dayton Springfield Rd
.UnitType = Apt
.UnitNumber= C

we lose anything after the space in the address, and although the DPV values indicate that the secondary address is invalid it does return DPV barcodes, Zip+4.

We have another piece of software for NCOA which does keep the data after the 'Apt C' and returns .unitnumber='C13' & 'C22'.