I have seen a video recently saying that in the two times Link goes back in time in the main quest of Ocarina of Time, he is creating an "Alternate Past". I do not think he is creating Alternat Past's, but staying in the same linear timeline. The two times that he had to go back in time were 1) to learn the song of storms 2) to get the gauntlets from the Spirit Temple. Both times, there is evidence it is a linear timeline up to this point. I will explain below.
In the first situation, if Link goes to Guru Guru as an adult he will say, "I'll never forget what happened on that day, seven years ago! Grrrrrrrrr! It's all that Ocarina kid's fault! Next time he comes around here, I'm gonna mess him up!" If Link wipes out his ocarina, Guru Guru will say, "What?! You've got an ocarina!! What the heck! That reminds me of that time, seven years ago! Back then a mean kid came here and played a strange song. It messed up this windmill! I'll never forget this song!" At this point, Guru Guru will teach you the Song of Storms, quite obviously the song that mean kid played seven years ago. Once Link learns and plays the song it will start to rain. Guru Guru will then say, "Oh, no! A strom again!! You played the Ocarina again, didn't you!! Grrrrrrrrrrrrrrr!!" Through these three lines, Guru Guru is telling us that Link has already been there in the past to play the Song of Stroms. This means that once Link does go back in time to do it for the first time, he is not entering an "Alternate Past", but the same past.
In the second situation, Link first goes to the Gerudo's Fortress and saves the four carpenters. By doing this he gets the Gerudo Membership Card. The one who gives it to him tells him that she is third-in-command behind Ganondorf and Nabooru. She says that Nabooru's headquarters are in the Spirit Temple, and thus Nabooru has left the fortress in her command. Once arriving at the Spirit Temple, there is no sign of Nabooru at all. NONE. However, once Link returns as a child, she is there. Once Link collects the Silver Gauntlets, he sees Twinrova capturing Nabooru. If she is captured in the past, and is not seen in the future, then it is hinting that it is again the same linear timeline, no third spilt.
The only time there is a legitimate spilt is when Zelda sends Link backs in time to "live out your childhood". There is the Adult Timeline, where Link and the sages have successfully sealed Ganondorf in the Sacred Realm. There is also the Child Timeline, where Link has been sent back in time to before he met Zelda by Zelda, and goes to see her and tells her Ganondorf's plans. Ganondorf is then sent to be executed. Two timelines.