To import data from one flat file into two or more FileMaker tables requires one import records operation for each target table in FileMaker.
I need to make sure that the id numbers are coinciding with each other
That is indeed the critical requirement. Is this an id number generated in the FileMaker contacts table or a value that is imported from the Excel file?
Without an ID number to import, you'll need to use a script to provide the needed values after the data has been imported. Replace Field Contents can be used in a script to assign serial numbers to the address field that match those of the newly imported contact records if you aren't importing an ID from the Excel file.
My thought is that the id would be generated by FM in the import of the names. The second import of the address, I am not sure how to reference the id numbers that were generated in the original import. Unless I am making it too hard and there is a easier, more efficient way.
A script can do what you need.
If you allow auto-enter operations when importing into the names table, each newly created record will get the next serial number value in the serial number sequence.
A script can then update the imported address records to match, but this also assumes that you have just one address per imported name and I don't know if this is the case or not....
After importing the addresses:
Go to Layout ["names" (Names)]
Go to Record/Request/Page [First]
Set Variable [$Start ; value: Names::__pkNameID ]
Go to Layout [Addresses]
Replace Field Contents [no dialog; Addresses::_fkNameID ; $Start + Get ( RecordNumber ) - 1]