How- seperate a combined list by filtering out first list of names

if i combined lists A and B of names into one list, how do I seperate them
again? Is there a way to filter out list A, leaving only list B remaining?

Is there a special character separating the firstname from the lastname, such as a space or pipe|?

If so, then you can easily do it with Data>Text to Columns using that character as the delimiter and then on the 3rd window, highlight column A and choose "do not import column(skip)". This will leave the select column(s) out.