Quote Originally Posted by Rynjin View Post
There are two Future Trunks timelines in Z; the one where Cell ambushes him after he gets back from the first time jump and the one where he comes back and kills the Androids and Cell.
The Trunks that died supposedly let his guard down because he thought everything was finished. There's also the question of why Cell didn't just eat the Future Trunks androids.

The way I saw it explained was this:

Timeline 1: Original timeline where Goku dies of a heart attack. Bulma invents a time machine and sends Trunks back.

Timeline 2: Same as the Prime timeline, except Cell isn't around. Bulma invents the remote detonator for the androids, and they are successfully used to blow up the androids. Trunks does not grow significantly stronger as he never needs to fight the androids, they're just blown up. Trunks returns to Timeline 1 and uses the remote detonator on the future androids. Cell discovers this, ambushes Trunks and kills him, then steals his time machine.

Timeline 3: A.k.a. the Prime Timeline, where the show happens. Cell arriving causes it to split off from Timeline 2 around the point where they discover the second time machine and Kami senses Cell drinking people. After everything is done, Trunks returns to Timeline 1 and kills the androids with strength rather than the remote detonator, and is ready for Cell's ambush and eliminates him.

Not sure if that's totally accurate (it's been a loooooong time since I watched myself) but it does track and leaves us with the correct number of Trunks and Cells running around.