When looking at the list of Prince of Tennis shows that I planned on watching, I noticed there existed Prince of Tennis: Another Story - Messages from Past and Future as well as Prince of Tennis: Another Story - Messages from Past and Future OVA Bonus. The first title has 4 episodes and the OVA Bonus has 2 so I assumed they were totally different. I wouldn't recommend searching around for these two similar but different titles of the show to watch because I discovered the OVA Bonus is actually just the first two episodes of the non-OVA Bonus title. In short, they are thesame, so I hope this advice saves you some time. I assume this site was just misinformed and it will be fixed eventually. At least it makes my list of completed shows one title longer XD.
On a review note, I really enjoyed these 4 extra episodes after finishing the actual Prince of Tennis series. They provided some great background history on some main characters I was curious about. The humor in the first two episodes got me goin hard at one point and another. In all, I really enjoyed these follow up episodes, they are worth the watch and only 20 minutes a piece generally.