Hi @ Adash,
The "Send email with options" would separate each option with a comma automatically, the flow wouldn't know which comma would separate the LastName and FirstName and combine the LastName and FirstName as a single option.
The only way to workaround it is delete or change the "," in the Name format (LastName, FirstName) before add it to the option.
You could create the flow to convert the Name format (LastName, FirstName) to (LastName FirstName) to achieve your needs.
I have made a test on my side ,Ihave create a excel table as below:

The screenshot of the flow as below:

The expression in the Condition as below:
concat(replace(items('Apply_to_each')?['Name'],',',' '),',')
The flow would run successfully to send the email with options as below:

The flow would run successfully as below:

Please let me know if your problem could be solved.
Regards,
Alice Zhang