That's not Ruby meeting her older self, and one version of older Ruby meeting another version of older Ruby. It's a meeting of Henceforward Ruby and 3.0 Ruby.

For those wondering what Henceforward is, it's a really popular AU come up by KumafromTaiwan, and this art piece is done by Dishwasher, a popular artist in the RWBY community due to their unrealistic speed and quality. Dishwasher is also currently in the process of making another really popular AU, called RWBY 3.0.

Kuma's AU is more "realistic" taking a few years in the future of the current canon, while Dish's AU is one that takes place many many years in the future, much more sci-fi than fantasy.