The fact that there were five predecessors in the shooting script, and five predecessors in Reloaded / Revolutions, very strongly suggests that they lifted and reworked that plot from the first movie, for reuse in the sequels.
From a narrative point of view, it would be confusing as hell to have five predecessors in this iteration of the matrix, as well as five predecessors across five previous iterations of the matrix.
Could both have been part of the same overarching, pre-planned plot? Sure. But is that likely? Not at all.
If Morpheus found 5 previous "The Ones", then I believe that there would still need to be 5 separate iterations of Neo, since after each iteration, the Architect wipes out Zion except for a small number of people that are used for repopulation. Morpheus would need to have been part of each of those genocides which he probably would have brought up in conversation.
the matrix could have gone trought 5 iteractions of the one cicle that morpheus knew nothing about, each resulting in the destruction of zion.
yet in this current version of the matrix, during this cicle, morpheus could have find 5 previous individuals that he tough were candidates to being the one, all that were ultimately not the one and who died fighting smith, before finaly finding neo the actual one for this latest cicle of the matrix.
From a narrative point of view, it would be confusing as hell to have five predecessors in this iteration of the matrix, as well as five predecessors across five previous iterations of the matrix.
Could both have been part of the same overarching, pre-planned plot? Sure. But is that likely? Not at all.