Shopify-api-node get both offline and online token

What I’m trying to say is that you wrote 2 code snippets that are doing the same thing:

// save offline token (session.accessToken)
      await Website.findOneAndUpdate(
        { shop: session.shop },
        { offline_token: session.accessToken }
      );

Is doing the same thing as this:

const session = await Shopify.Auth.validateAuthCallback(
        req,
        res,
        req.query
      );

So why include both because validateAuthCallback already stores the tokens in your database