Two duplicate indexes with the same columns

I am looking at a table in our database (I didn't make the table), and I see that there are 2 indexes that are exactly the same (I don't know why this was done) just named differently, can this have any negative affect on the table?

Take this example table:

create table mytable(
    mytable_id int unsigned primary key auto_increment,
    user_id int unsigned,
    amount decimal(12,2),
    index user_id_idx(user_id),
    index user_id_2(user_id)
);