Find duplicate words not line

Hi, I try to find a solution since last week but I still can’t so I hope you can help me.
I have two huge files (the first is has 2 million lines and the second one 200k) The first has a names and a telephone numbers and the second file has only names.
File one : John Smith:+355867522
Second file: John Smith
The files are not the same so I can’t make a comparison. I can’t find duplicates lines because of the telephone number.
I need to find how much from the people in the smaller list are in the bigger one, and if the is a success to add the telephone number there.
Or I other words filter the bigger file only the names from the small but with the phone number.
I have tried a million things but unfortunately-no luck.
I hope someone can help me.
Thanks in advance

Hi @Gabriela_Stefanova

Welcome to forum Final u need to.get no.of people whose name is in both files ?