How to use DB connections in Actix several times per function?

You just need to move the reference, not the connection itself:

async fn index(pool: web::Data<DbPool>, name: web::Path<(String)>) -> impl Responder {
    let name = name.into_inner();

    let conn_ = pool.get().expect("couldn't get db connection from pool");
    let conn = &conn_;
    let user1 = web::block(move || actions::insert_new_user(&conn, &user))
        .await
        .map_err(|e| {
            eprintln!("{}", e);
            HttpResponse::InternalServerError().finish()
        })?;

    // ... asynchronous code here

    let user2 = web::block(move || actions::insert_new_user(&conn, &user))
        .await
        .map_err(|e| {
            eprintln!("{}", e);
            HttpResponse::InternalServerError().finish()
        })?;
    
    Ok(HttpResponse::Ok().json(user))
}

Your problem can be reduced to (not working version):

struct Conn {}

fn foo(_: &Conn) {}


fn main() {

    let conn_ = Conn {};
    
    (move || foo(&conn_))();
    (move || foo(&conn_))();
    
}

Playground

Working version:

struct Conn {}

fn foo(_: &Conn) {}


fn main() {

    let conn_ = Conn {};
    let conn = &conn_;
    (move || foo(conn))();
    (move || foo(conn))();
    
}

Playground